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Recombinant Escherichia coli (E. coli) strain that produces phytochelatin (PC) and/or metallothionein (MT) can synthesize various metal nanoparticles (NPs) by reducing metal ions. Here we report in vivo biosynthesis of iron oxide nanocomposites (NCs) using recombinant E. coli. We designed a strategy of biosynthesizing iron oxide NCs by first internalizing chemically synthesized iron oxide NPs, followed by the reduction of added metal ions on the surface of internalized NPs by PC and/or MT in E. coli. For this, chemically synthesized Fe3O4 NPs were internalized by recombinant E. coli, and then, Au and Ag ions were added for the biosynthesis of AuFe3O4 and AgFe3O4 NCs, respectively. The NCs synthesized were analyzed by transmission electron microscopy, UV–vis spectrophotometry, and X-ray diffractometry to characterize their shape, optical property, and crystallinity. The Fe3O4 NPs in the biosynthesized NCs allowed easy purification of the biosynthesized NCs by applying a magnetic field. The AuFe3O4 NCs were used for enzyme-linked immunosorbent assay to detect prostate-specific antigen protein, while AgFe3O4 NCs were utilized for the antimicrobial application with low minimum inhibitory concentration. As recombinant E. coli can uptake and reduce various NPs and metal ions, biosynthesis of a wide range of NCs as new nanomaterials will be possible for diverse applications. Key points: • AuFe3O4 and AgFe3O4 nanocomposites were synthesized by recombinant E. coli. • Escherichia coli synthesized different iron oxide NCs depending on the metal ions to be added. • Biosynthesized AuFe3O4 NC was used for ELISA and AgFe3O4 NC for antimicrobial tests. [ABSTRACT FROM AUTHOR]

Perspective taking, one's knowledge of their own mental and emotional states and inferences about others' mental and emotional states, is an important skill for writing development. In the present study, we examined how perspective taking is expressed in writing and how it is related to overall writing quality. We analyzed seventh graders' source-based analytical essays (N = 195) to investigate (1) the extent to which students incorporated perspective taking in their essays, (2) how the extent of perspective taking in essays differ by students' sex and English learner status, and (3) the extent to which perspective taking in writing is associated with overall writing quality. Findings revealed that students wrote more from their own perspective than that of others. Moreover, the results of multi-level analyses suggested that female students exhibited more varied perspectives but there was no meaningful difference by English learner status. Lastly, greater extent of perspective taking, particularly that of higher level of perspectives (i.e., dual perspective), was associated with better writing quality, after accounting for students' demographic backgrounds (e.g., sex, poverty status, English learner status) and essay length. These results underscore the importance of writing from multiple perspectives on writing quality. [ABSTRACT FROM AUTHOR]

Electrically conductive epoxy composites were developed by adding cilia-like powders produced by dispersing multi-walled carbon nanotubes (MWNTs) on copper particles via mechanical milling. During the milling process, the MWNTs were gradually dispersed and partially embedded in the copper particles, producing cilialike powders that enhanced the electrical conductivity of the epoxy composites. With further milling, however, excessive embedding of the MWNTs in the copper particles resulted in decreased electrical conductivity. Electrical conductivity of the epoxy composites containing 24 vol.% of the cilia-like powders (milled for 1 h) was remarkably enhanced up to 15 S/cm. [ABSTRACT FROM AUTHOR]