273 research outputs found
Electronic structure, imaging contrast and chemical reactivity of graphene moir\'e on metals
Realization of graphene moir\'e superstructures on the surface of 4d and 5d
transition metals offers templates with periodically modulated electron
density, which is responsible for a number of fascinating effects, including
the formation of quantum dots and the site selective adsorption of organic
molecules or metal clusters on graphene. Here, applying the combination of
scanning probe microscopy/spectroscopy and the density functional theory
calculations, we gain a profound insight into the electronic and topographic
contributions to the imaging contrast of the epitaxial graphene/Ir(111) system.
We show directly that in STM imaging the electronic contribution is prevailing
compared to the topographic one. In the force microscopy and spectroscopy
experiments we observe a variation of the interaction strength between the tip
and high-symmetry places within the graphene moir\'e supercell, which determine
the adsorption cites for molecules or metal clusters on graphene/Ir(111).Comment: submitted on Sep, 6th 201
Strain and structure driven complex magnetic ordering of a CoO overlayer on Ir(100)
We have investigated the magnetic ordering in the ultrathin c(102)
CoO(111) film supported on Ir(100) on the basis of ab-initio calculations. We
find a close relationship between the local structural properties of the oxide
film and the induced magnetic order, leading to alternating ferromagnetically
and anti-ferromagnetically ordered segments. While the local magnetic order is
directly related to the geometric position of the Co atoms, the mismatch
between the CoO film and the Ir substrate leads to a complex long-range order
of the oxide.Comment: 5 pages, 4 figure
An Artificially Lattice Mismatched Graphene/Metal Interface: Graphene/Ni/Ir(111)
We report the structural and electronic properties of an artificial
graphene/Ni(111) system obtained by the intercalation of a monoatomic layer of
Ni in graphene/Ir(111). Upon intercalation, Ni grows epitaxially on Ir(111),
resulting in a lattice mismatched graphene/Ni system. By performing Scanning
Tunneling Microscopy (STM) measurements and Density Functional Theory (DFT)
calculations, we show that the intercalated Ni layer leads to a pronounced
buckling of the graphene film. At the same time an enhanced interaction is
measured by Angle-Resolved Photo-Emission Spectroscopy (ARPES), showing a clear
transition from a nearly-undisturbed to a strongly-hybridized graphene
-band. A comparison of the intercalation-like graphene system with flat
graphene on bulk Ni(111), and mildly corrugated graphene on Ir(111), allows to
disentangle the two key properties which lead to the observed increased
interaction, namely lattice matching and electronic interaction. Although the
latter determines the strength of the hybridization, we find an important
influence of the local carbon configuration resulting from the lattice
mismatch.Comment: 9 pages, 3 figures, Accepted for publication in Phys. Rev.
Tauroursodeoxycholic Acid May Improve Liver and Muscle but Not Adipose Tissue Insulin Sensitivity in Obese Men and Women
Endoplasmic Reticulum Stress Is Reduced in Tissues of Obese Subjects After Weight Loss
OBJECTIVE—Obesity is associated with insulin resistance and type 2 diabetes, although the mechanisms linking these pathologies remain undetermined. Recent studies in rodent models revealed endoplasmic reticulum (ER) stress in adipose and liver tissues and demonstrated that ER stress could cause insulin resistance. Therefore, we tested whether these stress pathways were also present in obese human subjects and/or regulated by weight loss
Recombinant Human Leptin Treatment Does Not Improve Insulin Action in Obese Subjects With Type 2 Diabetes
Random-phase approximation and its applications in computational chemistry and materials science
The random-phase approximation (RPA) as an approach for computing the
electronic correlation energy is reviewed. After a brief account of its basic
concept and historical development, the paper is devoted to the theoretical
formulations of RPA, and its applications to realistic systems. With several
illustrating applications, we discuss the implications of RPA for computational
chemistry and materials science. The computational cost of RPA is also
addressed which is critical for its widespread use in future applications. In
addition, current correction schemes going beyond RPA and directions of further
development will be discussed.Comment: 25 pages, 11 figures, published online in J. Mater. Sci. (2012
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