20 research outputs found
Tunable Hybridization Between Electronic States of Graphene and Physisorbed Hexacene
Non-covalent functionalization via physisorption of organic molecules
provides a scalable approach for modifying the electronic structure of graphene
while preserving its excellent carrier mobilities. Here we investigated the
physisorption of long-chain acenes, namely, hexacene and its fluorinated
derivative perfluorohexacene, on bilayer graphene for tunable graphene devices
using first principles methods. We find that the adsorption of these molecules
leads to the formation of localized states in the electronic structure of
graphene close to its Fermi level, which could be readily tuned by an external
electric field. The electric field not only creates a variable band gap as
large as 250 meV in bilayer graphene, but also strongly influences the charge
redistribution within the molecule-graphene system. This charge redistribution
is found to be weak enough not to induce strong surface doping, but strong
enough to help preserve the electronic states near the Dirac point of graphene.Comment: 17 pages, 7 figures, supporting informatio
Strong Oxidation Resistance of Atomically Thin Boron Nitride Nanosheets
Investigation on oxidation resistance of two-dimensional (2D) materials is
critical for many of their applications, because 2D materials could have higher
oxidation kinetics than their bulk counterparts due to predominant surface
atoms and structural distortions. In this study, the oxidation behavior of
high-quality boron nitride (BN) nanosheets of 1-4 layer thick has been examined
by heating in air. Atomic force microscopy and Raman spectroscopy analyses
reveal that monolayer BN nanosheets can sustain up to 850 {\deg}C and the
starting temperature of oxygen doping/oxidation of BN nanosheets only slightly
increases with the increase of nanosheet layer and depends on heating
conditions. Elongated etch lines are found on the oxidized monolayer BN
nanosheets, suggesting that the BN nanosheets are first cut along the
chemisorbed oxygen chains and then the oxidative etching grows perpendicularly
to these cut lines. The stronger oxidation resistance of BN nanosheets suggests
that they are more preferable for high-temperature applications than graphene
Low temperature transport on surface conducting diamond
Magneto-transport measurements were performed on surface conducting
hydrogen-terminated diamond (100) hall bars at temperatures between 0.1-5 K in
magnetic fields up to 8T.Comment: 2 pages Optoelectronic and Microelectronic Materials & Devices
(COMMAD), 2012 Conferenc
Proteomic and transcriptomic analysis of heart failure due to volume overload in a rat aorto-caval fistula model provides support for new potential therapeutic targets - monoamine oxidase A and transglutaminase 2
<p>Abstract</p> <p>Background</p> <p>Chronic hemodynamic overloading leads to heart failure (HF) due to incompletely understood mechanisms. To gain deeper insight into the molecular pathophysiology of volume overload-induced HF and to identify potential markers and targets for novel therapies, we performed proteomic and mRNA expression analysis comparing myocardium from Wistar rats with HF induced by a chronic aorto-caval fistula (ACF) and sham-operated rats harvested at the advanced, decompensated stage of HF.</p> <p>Methods</p> <p>We analyzed control and failing myocardium employing iTRAQ labeling, two-dimensional peptide separation combining peptide IEF and nano-HPLC with MALDI-MS/MS. For the transcriptomic analysis we employed Illumina RatRef-12v1 Expression BeadChip.</p> <p>Results</p> <p>In the proteomic analysis we identified 2030 myocardial proteins, of which 66 proteins were differentially expressed. The mRNA expression analysis identified 851 differentially expressed mRNAs.</p> <p>Conclusions</p> <p>The differentially expressed proteins confirm a switch in the substrate preference from fatty acids to other sources in the failing heart. Failing hearts showed downregulation of the major calcium transporters SERCA2 and ryanodine receptor 2 and altered expression of creatine kinases. Decreased expression of two NADPH producing proteins suggests a decreased redox reserve. Overexpression of annexins supports their possible potential as HF biomarkers. Most importantly, among the most up-regulated proteins in ACF hearts were monoamine oxidase A and transglutaminase 2 that are both potential attractive targets of low molecular weight inhibitors in future HF therapy.</p
Neural Knowledge Processing in Expert Systems
In this chapter the knowledge-based neurocomputing will be applied to expert systems. Two main approaches to represent the knowledge base, namely the explicit and implicit representations will first be introduced and compared in rule-based and neural expert systems, respectively. Then, several possible integration strategies that make an effort to eliminate the drawbacks of both approaches in hybrid systems, will be surveyed. To illustrate the full power of knowledge-based neurocomputing, the main ideas of the prototypical, strictly neural expert system MACIE will be sketched. Here, a neural network is enriched by other functionalities to achieve all required features of expert systems. The neural knowledge processing will further be demonstrated on the system EXPSYS which exploits the powerful back-propagation learning to automatically create the knowledge base. In addition, EXPSYS introduces the interval neuron states to cope with incomplete information and it provides a simple expla..
Electrical Double Layer at Various Electrode Potentials: A Modification by Vibration
This paper proposes a vibration model
of ions as an improvement over the conventional Gouy–Chapman–Stern
theory, which is used to model the electrical double layer capacitance
and to study the ionic dynamics at electrode/electrolyte interfaces.
Although the Gouy–Chapman–Stern model is successful
for small applied potentials, it fails to explain the observed behavior
at larger potentials, which are becoming increasingly important as
materials with high charge injection capacities are developed. A time-dependent
study on ionic transport indicates that ions vibrate near the electrode
surface in response to the applied electric field. This vibration
allows us to correctly predict the experimentally observed decreasing
differential capacitance at high electrode potential. This new model
elucidates the mechanism behind the ionic dynamics at solid–electrolyte
interfaces, providing useful insight that may be applied to many electrochemical
systems in energy storage, photoelectrochemical cells, and biosensing