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131.
Molecular dynamics simulation are used to examine the effect of a uniform perpendicular magnetic field on a two-dimensional interacting electron system. In this simulation we include the effect of the magnetic field classically through the Lorentz force. Both the Coulomb and the magnetic forces are included directly in the electron dynamics to study their combined effect on the dynamical properties of the 2D system. Results are presented for the velocity autocorrelation function and the diffusion constants in the presence and absence of an external magnetic field. Our simulation results clearly show that the external magnetic field has an effect on the dynamical properties of the system. 相似文献
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R. Wyss A. Johnson D. J. G. Love M. J. Godfrey S. M. Mullins 《Zeitschrift für Physik A Hadrons and Nuclei》1989,332(2):241-242
The level scheme of the yrast band of124Ba has been extended up to spin 32?. Transitions in the two negative parity side bands are observed up to spin 27? and tentatively 20?. The second backbend observed in the S-band and the backbends in the side bands are explained as due to neutrons. The structure of the sidebands is discussed and compared with deformation self-consistent calculations, Total Routhian Surfaces (TRS). 相似文献
134.
Conrad S. Lovell Jin Ho Kang Godfrey Sauti James M. Fitz‐Gerald Cheol Park 《Journal of Polymer Science.Polymer Physics》2010,48(22):2355-2365
Single‐wall carbon nanotubes (SWCNTs) have been added to high molecular weight poly(γ‐benzyl‐L ‐glutamate), or PBLG, to evaluate their effects on the polymer's shear piezoelectricity. While the addition of SWCNTs increased various PBLG physical properties such as electrical conductivity, dielectric constant, several mechanical properties, and electrostriction coefficient, the shear piezoelectricity remained constant up to a 0.3 wt % SWCNT concentration. The composite crystallinity, orientation, and SWCNT alignment (measured by X‐ray diffraction, birefringence, and polarized Raman spectroscopy, respectively) were found to be constant up to this same concentration, corroborating the shear piezoelectric findings. PBLG composites made with acid‐treated (and therefore less electrically conductive) SWCNTs exhibited similar shear piezoelectric behavior, indicating that neither the SWCNT type, concentration (up to the percolation threshold), nor electrical conductivity influences PBLG shear piezoelectricity. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2010 相似文献
135.
The tribological and tribochemical properties of 5-10 nm thick Ag films sliding on various metal and inorganic substrates were measured using a surface forces apparatus coupled with ex situ x-ray photoelectron spectroscopy. We observed enhanced chemical reactivity in the sheared regions compared to the unsheared regions, which we attribute to significant frictional heating in agreement with two recent simulations. It is also found that the initial topography (roughness) of the films plays a significant role in determining the friction, wear, and tribochemical reactions. The larger the surface roughness, the larger are the friction coefficients. Initially smooth surfaces, forming large continuous junctions, create large wear debris particles; whereas initially rough surfaces, forming many small junctions, create many small particles. Even though initially smooth surfaces are chemically less reactive than initially rough surfaces, they are tribochemically more reactive, forming two to three times more oxides of silver during shearing than under static conditions and organometals of silver that under normal (static) conditions do not form. The chemical reactions observed cannot be explained without including the tribological processes, such as the local stresses, temperature rises, and type of wear produced by the shearing surfaces. 相似文献
136.
Akbulut M Godfrey Alig AR Israelachvili J 《The journal of physical chemistry. B》2006,110(44):22271-22278
Using a modified surface forces apparatus, we have simultaneously measured the friction and triboelectrification between both similar and dissimilar molecularly smooth hexadecanethiol-coated metal surfaces on mica substrates. On shearing dissimilar surfaces, the tribocurrent increases dramatically as the load or pressure is increased, with large fluctuations about the mean. Neither charge transfer nor fluctuations are observed when the symmetric surfaces are sheared against each other. We also find that the type of friction, i.e., stick-slip or smooth sliding, the load and friction force, the sliding distance, and recent previous history have additional fine influences on the triboelectrification. Our results suggest that frictional dissipation induces electron-hole formation and charge transfer between two shearing surfaces due to molecular-level roughness and defects and local dielectric constant changes, giving rise to the observed tribocurrents. 相似文献
137.
New neutral gauge bosons (Z' 's) are predicted by many models of physics beyond the standard electroweak theory. It is possible that a Z' will be discovered by the Large Hadron Collider program. The next step would be to measure its properties to identify the underlying theory that gave rise to the Z'. Heavy quarks have the unique property that they can be identified in the final states. In this Letter we demonstrate that measuring Z' decays to b- and t-quark final states can act as an effective means of discriminating between models with extra gauge bosons. 相似文献
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