178 research outputs found
Shall Be Bright at Last: Reflections on Suffering and Hope in the Letters of Paul
These nine essays on suffering offer exercises in Christian hope. The contributors reveal honest and tender wounds of the many harsh realities of life in a broken world awaiting full redemption. They meditate on Paul\u27s holy words that teach us to pray with expectation and live by faith. They encourage fellow pilgrims to trust the path and stick together.
Shall Be Bright at Last is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.
CC BY-NC-SAhttps://digitalcommons.georgefox.edu/monographs/1000/thumbnail.jp
Direct observation of a highly spin-polarized organic spinterface at room temperature
The design of large-scale electronic circuits that are entirely
spintronics-driven requires a current source that is highly spin-polarised at
and beyond room temperature, cheap to build, efficient at the nanoscale and
straightforward to integrate with semiconductors. Yet despite research within
several subfields spanning nearly two decades, this key building block is still
lacking. We experimentally and theoretically show how the interface between Co
and phthalocyanine molecules constitutes a promising candidate. Spin-polarised
direct and inverse photoemission experiments reveal a high degree of spin
polarisation at room temperature at this interface. We measured a magnetic
moment on the molecules's nitrogen pi orbitals, which substantiates an
ab-initio theoretical description of highly spin-polarised charge conduction
across the interface due to differing spinterface formation mechanims in each
spin channel. We propose, through this example, a recipe to engineer simple
organic-inorganic interfaces with remarkable spintronic properties that can
endure well above room temperature
Quasiparticle bandgap engineering of graphene and graphone on hexagonal boron nitride substrate
Graphene holds great promise for post-silicon electronics, however, it faces
two main challenges: opening up a bandgap and finding a suitable substrate
material. In principle, graphene on hexagonal boron nitride (hBN) substrate
provides potential system to overcome these challenges. Recent theoretical and
experimental studies have provided conflicting results: while theoretical
studies suggested a possibility of a finite bandgap of graphene on hBN, recent
experimental studies find no bandgap. Using the first-principles density
functional method and the many-body perturbation theory, we have studied
graphene on hBN substrate. A Bernal stacked graphene on hBN has a bandgap on
the order of 0.1 eV, which disappears when graphene is misaligned with respect
to hBN. The latter is the likely scenario in realistic devices. In contrast, if
graphene supported on hBN is hydrogenated, the resulting system (graphone)
exhibits bandgaps larger than 2.5 eV. While the bandgap opening in graphene/hBN
is due to symmetry breaking and is vulnerable to slight perturbation such as
misalignment, the graphone bandgap is due to chemical functionalization and is
robust in the presence of misalignment. The bandgap of graphone reduces by
about 1 eV when it is supported on hBN due to the polarization effects at the
graphone/hBN interface. The band offsets at graphone/hBN interface indicate
that hBN can be used not only as a substrate but also as a dielectric in the
field effect devices employing graphone as a channel material. Our study could
open up new way of bandgap engineering in graphene based nanostructures.Comment: 8 pages, 4 figures; Nano Letters, Publication Date (Web): Oct. 25
2011, http://pubs.acs.org/doi/abs/10.1021/nl202725
Effect of Layer-Stacking on the Electronic Structure of Graphene Nanoribbons
The evolution of electronic structure of graphene nanoribbons (GNRs) as a
function of the number of layers stacked together is investigated using
\textit{ab initio} density functional theory (DFT) including interlayer van der
Waals interactions. Multilayer armchair GNRs (AGNRs), similar to single-layer
AGNRs, exhibit three classes of band gaps depending on their width. In zigzag
GNRs (ZGNRs), the geometry relaxation resulting from interlayer interactions
plays a crucial role in determining the magnetic polarization and the band
structure. The antiferromagnetic (AF) interlayer coupling is more stable
compared to the ferromagnetic (FM) interlayer coupling. ZGNRs with the AF
in-layer and AF interlayer coupling have a finite band gap while ZGNRs with the
FM in-layer and AF interlayer coupling do not have a band gap. The ground state
of the bi-layer ZGNR is non-magnetic with a small but finite band gap. The
magnetic ordering is less stable in multilayer ZGNRs compared to single-layer
ZGNRs. The quasipartcle GW corrections are smaller for bilayer GNRs compared to
single-layer GNRs because of the reduced Coulomb effects in bilayer GNRs
compared to single-layer GNRs.Comment: 10 pages, 5 figure
Contribution to the understanding of tribological properties of graphite intercalation compounds with metal chloride
Intrinsic tribological properties of lamellar compounds are usually attributed to the presence of van der Waals gaps in their structure through which interlayer interactions are weak. The controlled variation of the distances and interactions between graphene layers by intercalation of electrophilic species in graphite is used in order to explore more deeply the friction reduction properties of low-dimensional compounds. Three graphite intercalation compounds with antimony pentachloride, iron trichloride and aluminium trichloride are studied. Their tribological properties are correlated to their structural parameters, and the interlayer interactions are deduced from ab initio bands structure calculations
On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection
A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)
Assessment of erosion, deposition and fuel retention in the JET-ILW divertor from ion beam analysis data
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