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ItemA tight binding and (k)over-right-arrow . (p)over-right-arrow study of monolayer staneneJiang, L ; Marconcini, P ; Hossian, MS ; Qiu, W ; Evans, R ; Macucci, M ; Skafidas, E (NATURE RESEARCH, 2017-09-21)Stanene is a single layer of tin atoms which has been discovered as an emerging material for quantum spin Hall related applications. In this paper, we present an accurate tight-binding model for single layer stanene near the Fermi level. We parameterized the onsite and hopping energies for the nearest, second nearest, and third nearest neighbor tight-binding method, both without and with spin orbital coupling. We derived the analytical solution for the [Formula: see text]and [Formula: see text] points and numerically investigated the buckling effect on the material electronic properties. In these points of the reciprocal space, we also discuss a corresponding [Formula: see text] description, obtaining the value of the [Formula: see text] parameters both analytically from the tight-binding ones, and numerically, fitting the ab-initio dispersion relations. Our models provide a foundation for large scale atomistic device transport calculations.
ItemPhenotypic and Functional Characterization of Peripheral Sensory Neurons derived from Human Embryonic Stem CellsAlshawaf, AJ ; Viventi, S ; Qiu, W ; D'Abaco, G ; Nayagam, B ; Erlichster, M ; Chana, G ; Everall, I ; Ivanusic, J ; Skafidas, E ; Dottori, M (NATURE PUBLISHING GROUP, 2018-01-12)The dorsal root ganglia (DRG) consist of a multitude of sensory neuronal subtypes that function to relay sensory stimuli, including temperature, pressure, pain and position to the central nervous system. Our knowledge of DRG sensory neurons have been predominantly driven by animal studies and considerably less is known about the human DRG. Human embryonic stem cells (hESC) are valuable resource to help close this gap. Our previous studies reported an efficient system for deriving neural crest and DRG sensory neurons from hESC. Here we show that this differentiation system gives rise to heterogeneous populations of sensory neuronal subtypes as demonstrated by phenotypic and functional analyses. Furthermore, using microelectrode arrays the maturation rate of the hESC-derived sensory neuronal cultures was monitored over 8 weeks in culture, showing their spontaneous firing activities starting at about 12 days post-differentiation and reaching maximum firing at about 6 weeks. These studies are highly valuable for developing an in vitro platform to study the diversity of sensory neuronal subtypes found within the human DRG.
ItemEnergy-filtered Electron Transport Structures for Low-power Low-noise 2-D ElectronicsPan, X ; Qiu, W ; Skafidas, E (NATURE PUBLISHING GROUP, 2016-10-31)In addition to cryogenic techniques, energy filtering has the potential to achieve high-performance low-noise 2-D electronic systems. Assemblies based on graphene quantum dots (GQDs) have been demonstrated to exhibit interesting transport properties, including resonant tunnelling. In this paper, we investigate GQDs based structures with the goal of producing energy filters for next generation lower-power lower-noise 2-D electronic systems. We evaluate the electron transport properties of the proposed GQD device structures to demonstrate electron energy filtering and the ability to control the position and magnitude of the energy passband by appropriate device dimensioning. We also show that the signal-to-thermal noise ratio performance of the proposed nanoscale device can be modified according to device geometry. The tunability of two-dimensional GQD structures indicates a promising route for the design of electron energy filters to produce low-power and low-noise electronics.