14,787 research outputs found
Energetics and kinetics of Li intercalation in irradiated graphene scaffolds
In the present study we investigate the irradiation-defects hybridized
graphene scaffold as one potential building material for the anode of Li-ion
batteries. Designating the Wigner V22 defect as a representative, we illustrate
the interplay of Li atoms with the irradiation-defects in graphene scaffolds.
We examine the adsorption energetics and diffusion kinetics of Li in the
vicinity of a Wigner V22 defect using density functional theory calculations.
The equilibrium Li adsorption sites at the defect are identified and shown to
be energetically preferable to the adsorption sites on pristine (bilayer)
graphene. Meanwhile the minimum energy paths and corresponding energy barriers
for Li migration at the defect are determined and computed. We find that while
the defect is shown to exhibit certain trapping effects on Li motions on the
graphene surface, it appears to facilitate the interlayer Li diffusion and
enhance the charge capacity within its vicinity because of the reduced
interlayer spacing and characteristic symmetry associated with the defect. Our
results provide critical assessment for the application of irradiated graphene
scaffolds in Li-ion batteries.Comment: 23 pages, 5 figure
Strong and Confined Acids Enable a Catalytic Asymmetric Nazarov Cyclization of Simple Divinyl Ketones
We report a catalytic asymmetric Nazarov cyclization of simple, acylic, alkyl-substituted divinyl ketones using our recently disclosed strong and confined imidodiphosphorimidate Brønsted acids. The corresponding monocyclic cyclopentenones are formed in good yields and excellent regio-, diastereo-, and enantioselectivities. Further, the chemical utility of the obtained enantiopure cyclopentenones is demonstrated
Performance Analysis of a Dual-Hop Cooperative Relay Network with Co-Channel Interference
This paper analyzes the performance of a dual-hop amplify-and-forward (AF) cooperative relay network in the presence of direct link between the source and destination and multiple co-channel interferences (CCIs) at the relay. Specifically, we derive the new analytical expressions for the moment generating function (MGF) of the output signal-to-interference-plus-noise ratio (SINR) and the average symbol error rate (ASER) of the relay network. Computer simulations are given to confirm the validity of the analytical results and show the effects of direct link and interference on the considered AF relay network
Turbulence control by developing a spiral wave with a periodic signal injection in the complex Ginzburg-Landau equation
Turbulence control in the two-dimensional complex Ginzburg-Landau equation is
investigated. A new approach is proposed for the control purpose. In the
presence of a small spiral wave seed initiation, a fully developed turbulence
can be completely annihilated by injecting a single periodic signal to a small
fixed space area around the spiral wave tip. The control is achieved in a
parameter region where the spiral wave of the uncontrolled system is absolutely
unstable. The robustness, convenience and high control efficiency of this
method is emphasized, and the mechanism underlying these practical advantages
are intuitively understood.Comment: 12 pages, figures can be found in the following journa
Truth Discovery in Crowdsourced Detection of Spatial Events
ACKNOWLEDGMENTS This research is based upon work supported in part by the US ARL and UK Ministry of Defense under Agreement Number W911NF-06-3-0001, and by the NSF under award CNS-1213140. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views or represent the official policies of the NSF, the US ARL, the US Government, the UK Ministry of Defense or the UK Government. The US and UK Governments are authorized to reproduce and distribute reprints for Government purposes notwithstanding any copyright notation hereon.Peer reviewedPostprin
Backaction of a charge detector on a double quantum dot
We develop a master equation approach to study the backaction of quantum
point contact (QPC) on a double quantum dot (DQD) at zero bias voltage. We
reveal why electrons can pass through the zero-bias DQD only when the bias
voltage across the QPC exceeds a threshold value determined by the eigenstate
energy difference of the DQD. This derived excitation condition agrees well
with experiments on QPC-induced inelastic electron tunneling through a DQD [S.
Gustavsson et al., Phys. Rev. Lett. 99, 206804(2007)]. Moreover, we propose a
new scheme to generate a pure spin current by the QPC in the absence of a
charge current.Comment: 6 pages, 4 figure
Cooling a nanomechanical resonator by a triple quantum dot
We propose an approach for achieving ground-state cooling of a nanomechanical
resonator (NAMR) capacitively coupled to a triple quantum dot (TQD). This TQD
is an electronic analog of a three-level atom in configuration which
allows an electron to enter it via lower-energy states and to exit only from a
higher-energy state. By tuning the degeneracy of the two lower-energy states in
the TQD, an electron can be trapped in a dark state caused by destructive
quantum interference between the two tunneling pathways to the higher-energy
state. Therefore, ground-state cooling of an NAMR can be achieved when
electrons absorb readily and repeatedly energy quanta from the NAMR for
excitations.Comment: 6 pages, 3 figure
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