We investigate the stability and phase transition of localized modes in Bose–Einstein Condensates (BECs) in an optical lattice with the discrete nonlinear Schrödinger model by considering both two- and three-body interactions. We find that there are three types of localized modes, bright discrete breather (DB), discrete kink (DK), and multi-breather (MUB). Moreover, both two- and three-body on-site repulsive interactions can stabilize DB, while on-site attractive three-body interactions destabilize it. There is a critical value for the three-body interaction with which both DK and MUB become the most stable ones. We give analytically the energy thresholds for the destabilization of localized states and find that they are unstable (stable) when the total energy of the system is higher (lower) than the thresholds. The stability and dynamics characters of DB and MUB are general for extended lattice systems. Our result is useful for the blocking, filtering, and transfer of the norm in nonlinear lattices for BECs with both two- and three-body interactions. 相似文献
286 , 176 (1996)]. (1) The interdiffusion critical wavelengths were calculated as 2.00–2.04 nm at temperatures ranging from 473
to 523 K, which is equal to those of Co/C multilayers within the experimental error, indicating that the interdiffusion behaviours
in the CoN/CN multilayers are still decided by the thermodynamic properties of the Co-C system. (2) The effective interdiffusivities
and macroscopic diffusion coefficients are smaller. (3) The activation energy for diffusion is larger. The features imply
that it is possible to improve the thermal stability of Co/C multilayers by doping with N atoms.
The high-temperature annealing results imply that the destructive threshold of the CoN/CN multilayers is 100–200 °C higher
than that of Co/C multilayers. The small-angle X-ray diffraction of CoN/CN soft X-ray multilayers indicates that the period
expansion of the multilayers is only 4% at 400 °C, and the interface pattern still exists even if they were annealed at 700 °C.
The large-angle X-ray diffraction and transmission electron microscopy analysis reveal that the crystalline process is significantly
retarded if doped with N atoms, leading to a smaller grain size at higher annealing temperatures.
The significant improvement of the thermal stability can be interpreted with Raman spectroscopy and X-ray photoelectron spectroscopy
analysis. The Raman spectra give the evidence that the formation of the sp3 bonding in the CN sublayers can be suppressed effectively by doping with N atoms, and thus the period expansion resulting
from the changes in the density of CN layers can be decreased considerably. The X-ray photoelectron spectra give information
about existence of the strong covalent bonding between N atoms and the ionic bonding between Co and N atoms, which can slow
down the tendency of the structural relaxation. The interstitial N atoms decrease the mobility of Co atoms, and thus the fcc
Co and hcp Co coexist even though the annealing temperature is much higher than the phase transformation temperature of 420 °C,
leading to the suppression of the grain growth.
Received: 29 May 1997/Accepted: 8 September 1997 相似文献
Here, two series of novel ursolic acid-based 1,2,4-triazolo[1,5-a]pyrimidines derivatives were synthesized and screened for their anti-inflammatory activity by evaluating their inhibition effect of using LPS-induced inflammatory response in RAW 264.7 macrophages in vitro; the effects of different concentrations of the compounds on the secretion of nitric oxide (NO) and inflammatory cytokines including TNF-α and IL-6 were evaluated. Their toxicity was also assessed in vitro. Results showed that the most prominent compound 3 could significantly decrease production of the above inflammatory factors. Docking study was performed for the representative compounds 3, UA, and Celecoxib to explain their interaction with cyclooxygenase-2 (COX-2) receptor active site. In vitro enzyme study implied that compound 3 exerted its anti-inflammatory activity through COX-2 inhibition.
The dynamics of the optomechanical entanglement between optical cavity field modes and a macroscopic mechanical breathing mode in a whispering-gallery cavity as well as the continuous variable entanglement between the phase-quadrature amplitudes of the two whispering-gallery modes have been analysed. Simulated results indicate that under state-of-the-art experimental conditions, optomechanical entanglement is obvious and can occur even at temperatures of above 40 K. Compared with the entanglement of the mechanical oscillator at the ground state temperature, optomechanical entanglement is more intense by several orders of magnitude. 相似文献