Effect of uniaxial strain on the site occupancy of hydrogen in vanadium from density-functional calculations

We investigate the influence of uniaxial strain on site occupancy of hydrogen vanadium, using density functional theory. The site occupancy is found to be strongly influenced by the strain state of the lattice. The results provide the conceptual framework of the atomistic description of the observed hysteresis in the alpha to beta phase transition in bulk, as well as the preferred octahedral occupancy of hydrogen in strained V layers

On the structural and energetic properties of the hydrogen absorber Li2Mg(NH)2

The authors have performed density functional theory based calculations of several possible conformations for the crystal structure of Li2Mg(NH)2 and they confirm the α phase, resolved from both x-ray and neutron diffraction data, as the ground-state configuration. It is also found that although the N–H bond is stronger in Li2Mg(NH)2 than in Li2NH, hydrogen release from Li2Mg(NH)2/LiH mixture displays more favorable thermodynamics than that from the Li2NH∕LiH mixture. The insights gained from this seemingly counterintuitive result should prove helpful in the search for promising hydrogen storage materials

Functionalized nanopore-embedded electrodes for rapid DNA sequencing

The determination of a patient's DNA sequence can, in principle, reveal an increased risk to fall ill with particular diseases [1,2] and help to design "personalized medicine" [3]. Moreover, statistical studies and comparison of genomes [4] of a large number of individuals are crucial for the analysis of mutations [5] and hereditary diseases, paving the way to preventive medicine [6]. DNA sequencing is, however, currently still a vastly time-consuming and very expensive task [4], consisting of pre-processing steps, the actual sequencing using the Sanger method, and post-processing in the form of data analysis [7]. Here we propose a new approach that relies on functionalized nanopore-embedded electrodes to achieve an unambiguous distinction of the four nucleic acid bases in the DNA sequencing process. This represents a significant improvement over previously studied designs [8,9] which cannot reliably distinguish all four bases of DNA. The transport properties of the setup investigated by us, employing state-of-the-art density functional theory together with the non-equilibrium Green's Function method, leads to current responses that differ by at least one order of magnitude for different bases and can thus provide a much more robust read-out of the base sequence. The implementation of our proposed setup could thus lead to a viable protocol for rapid DNA sequencing with significant consequences for the future of genome related research in particular and health care in general.Comment: 12 pages, 5 figure