DNA-Driven Dynamic Assembly of MoS2 Nanosheets

Controlling the assembly of molybdenum disulfide (MoS2) layers into static and dynamic superstructures can impact on their use in optoelectronics, energy, and drug delivery. Toward this goal, we present a strategy to drive the assembly of MoS2 layers via the hybridization of complementary DNA linkers. By functionalizing the MoS2 surface with thiolated DNA, MoS2 nanosheets were assembled into mulitlayered superstructures, and the complementary DNA strands were used as linkers. A disassembly process was triggered by the formation of an intramolecular i-motif structure at a cystosine-rich sequence in the DNA linker at acidic pH values. We tested the versatility of our approach by driving the disassembly of the MoS2 superstructures through a different DNA-based mechanism, namely strand displacement. This study demonstrates how DNA can be employed to drive the static and dynamic assembly of MoS2 nanosheets in aqueous solution

Microstructural evolution during ageing of Al-Cu-Li-x alloys

In this study, atom probe tomography was used to investigate the microstructure of the alloy AA2198 (Al–1.35 Cu–3.55 Li–0.29 Mg–0.08 Ag) over a range of ageing conditions to examine the evolution of phases in the alloy, in particular aiming to reveal the nucleation mechanism of the strengthening T1 phase. T1 precursor phases were observed from early ageing, most of which were connected to dislocations enriched with Mg and Ag. This Mg solute segregation on the dislocations was subsequently observed to develop into S-like phases. Ag and Mg segregation to T1 interfaces was systematically observed when the plates were oriented perpendicular to the probing direction. The matrix solute content was followed during the course of T1 precipitation. It was found that the evolution of Cu, Li, Mg and Ag was similar, giving additional evidence for their co-precipitation

Polar nano-clusters in nominally paraelectric ceramics demonstrating high microwave tunability for wireless communication

Dielectric materials, with high tunability at microwave frequencies, are key components in the design of microwave communication systems. Dense Ba0.6Sr0.4TiO3 (BST) ceramics, with different grain sizes, were prepared in order to optimise the dielectric tunability via polar nano cluster effects. Dielectric permittivity and loss measurements were performed at both high and low frequencies and were supported by results from X-ray powder diffraction, scanning and transmission electron microscopies, Raman spectroscopy and piezoresponse force microscopy. The concentration of polar nano clusters, whose sizes are found to be in the range 20–50 nm, and the dielectric tunability increase with increasing grain size. A novel method for measurement of the microwave tunability in bulk dielectrics is presented. The highest tunability of 32 % is achieved in ceramics with an average grain size of 10 μm. The tunability of BST ceramics with applied DC field is demonstrated in a prototype small resonant antenna

Threeâ dimensional imaging of shear bands in bulk metallic glass composites

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134811/1/jmi12443_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134811/2/jmi12443.pd

DNA-Driven Dynamic Assembly of MoS2 Nanosheets

Xenorhabdus strains from entomopathogenic nematodes isolated from United Kingdom soils by using the insect bait entrapment method were characterized by partial sequencing of the 16S rRNA gene, four housekeeping genes (asd, ompR, recA, and serC) and the flagellin gene (fliC). Most strains (191/197) were found to have genes with greatest similarity to those of Xenorhabdus bovienii, and the remaining six strains had genes most similar to those of Xenorhabdus nematophila. Generally, 16S rRNA sequences and the sequence types based on housekeeping genes were in agreement, with a few notable exceptions. Statistical analysis implied that recombination had occurred at the serC locus and that moderate amounts of interallele recombination had also taken place. Surprisingly, the fliC locus contained a highly variable central region, even though insects lack an adaptive immune response, which is thought to drive flagellar variation in pathogens of higher organisms. All the X. nematophila strains exhibited a consistent pattern of insecticidal activity, and all contained the insecticidal toxin genes xptA1A2B1C1, which were present on a pathogenicity island (PAI). The PAIs were similar among the X. nematophila strains, except for partial deletions of a peptide synthetase gene and the presence of insertion sequences. Comparison of the PAI locus with that of X. bovienii suggested that the PAI integrated into the genome first and then acquired the xpt genes. The independent mobility of xpt genes was further supported by the presence of xpt genes in X. bovienii strain 173 on a type 2 transposon structure and by the variable patterns of insecticidal activity in X. bovienii isolates, even among closely related strains

Microstructural evolution during ageing of Al-Cu-Li-x alloys

International audienceIn this study, atom probe tomography was used to investigate the microstructure of the alloy AA2198 (Al-1.35 Cu-3.55 Li-0.29 Mg-0.08 Ag) over a range of ageing conditions to examine the evolution of phases in the alloy, in particular aiming to reveal the nucleation mechanism of the strengthening T-1 phase. T-1 precursor phases were observed from early ageing, most of which were connected to dislocations enriched with Mg and Ag. This Mg solute segregation on the dislocations was subsequently observed to develop into S-like phases. Ag and Mg segregation to T-1 interfaces was systematically observed when the plates were oriented perpendicular to the probing direction. The matrix solute content was followed during the course of T-1 precipitation. It was found that the evolution of Cu, Li, Mg and Ag was similar, giving additional evidence for their co-precipitation

Using Small Angle Scattering and Atom Probe Tomography as Complementary Tools for Characterising Precipitate Microstructures at the Nanoscale

International audienc

Using Small Angle Scattering and Atom Probe Tomography as Complementary Tools for Characterising Precipitate Microstructures at the Nanoscale

International audienc

Using Small Angle Scattering and Atom Probe Tomography as Complementary Tools for Characterising Precipitate Microstructures at the Nanoscale

International audienc