110,267 research outputs found
Kinetics of dissociative chemisorption of methane and ethane on Pt(110)-(1X2)
The initial probability of dissociative chemisorption Pr of methane and ethane on the highly corrugated, reconstructed Pt(110)â(1Ă2) surface has been measured in a microreactor by counting the number of carbon atoms on the surface following the reaction of methane and ethane on the surface which was held at various constant temperatures between 450 and 900 K during the reaction. Methane dissociatively chemisorbs on the Pt(110)â(1Ă2) surface with an apparent activation energy of 14.4 kcal/mol and an apparent preexponential factor of 0.6. Ethane chemisorbs dissociatively with an apparent activation energy of 2.8 kcal/mol and an apparent preexponential factor of 4.7Ă10^(â3). Kinetic isotope effects were observed for both reactions. The fact that P_r is a strong function of surface temperature implies that the dissociation reactions proceed via a trappingâmediated mechanism. A model based on a trappingâmediated mechanism is used to explain the observed kinetic behavior. Kinetic parameters for CâH bond dissociation of the thermally accommodated methane and ethane are extracted from the model
Quantum sensing of rotation velocity based on transverse field Ising model
We study a transverse-field Ising model (TFIM) in a rotational reference
frame. We find that the effective Hamiltonian of the TFIM of this system
depends on the system's rotation velocity. Since the rotation contributes an
additional transverse field, the dynamics of TFIM sensitively responses to the
rotation velocity at the critical point of quantum phase transition. This
observation means that the TFIM can be used for quantum sensing of rotation
velocity that can sensitively detect rotation velocity of the total system at
the critical point. It is found that the resolution of the quantum sensing
scheme we proposed is characterized by the half-width of Loschmidt echo of the
dynamics of TFIM when it couples to a quantum system S. And the resolution of
this quantum sensing scheme is proportional to the coupling strength \delta
between the quantum system S and the TFIM, and to the square root of the number
of spins N belonging the TFIM.Comment: 6 pages,6 figure
Electroencephalogram evidence for the activation of human mirror neuron system during the observation of intransitive shadow and line drawing actions
This article is available open access from the NCBI website at the link below. Copyright 2013 © Neural Regeneration Research. This is an open-access article distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 3.0 Unported, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Previous studies have demonstrated that hand shadows may activate the motor cortex associated with the mirror neuron system in human brain. However, there is no evidence of activity of the human mirror neuron system during the observation of intransitive movements by shadows and line drawings of hands. This study examined the suppression of electroencephalography mu waves (8â13 Hz) induced by observation of stimuli in 18 healthy students. Three stimuli were used: real hand actions, hand shadow actions and actions made by line drawings of hands. The results showed significant desynchronization of the mu rhythm (âmu suppressionâ) across the sensorimotor cortex (recorded at C3, Cz and C4), the frontal cortex (recorded at F3, Fz and F4) and the central and right posterior parietal cortex (recorded at Pz and P4) under all three conditions. Our experimental findings suggest that the observation of âimpoverished hand actionsâ, such as intransitive movements of shadows and line drawings of hands, is able to activate widespread cortical areas related to the putative human mirror neuron system.The National Natural Science Foundation of China and the Research Fund for the Doctoral Program of Higher Education of China
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