Wang D.-H.,Ludong University
Current Applied Physics | Year: 2011
It is a well-known fact that the surfaces can affect the photodetachment of negative ion. In this paper, we focus on how the photodetachment cross-section of H- is altered when it is placed near two perpendicular metal surfaces. We begin by briefly presenting the electrostatic image potential of the detached electron caused by the metal surfaces, then we study the classical motion of the photo-detached electron near two perpendicular metal surfaces. The photodetachment cross-section of this system has been derived and calculated based on the closed orbit theory. The results show that the cross-section depends on the photon energy and the ion-surface distances sensitively. Compared to the case of the photodetachment of H- near one metal surface, the oscillatory structure in the cross-section of our system becomes much more complicated. This study provides a new understanding on the photodetachment process of negative ion or atoms in the vicinity of surfaces or cavities. © 2011 Elsevier B.V. All rights reserved.
Gong Y.,Ludong University
Physica A: Statistical Mechanics and its Applications | Year: 2011
In this paper, by introducing a particular kind of parametric non-Gaussian noise (NGN) via the inositol triphosphate (IP 3), we study the effect of the NGN's deviation q from the Gaussian noise and its correlation time τ, as well as the cell number N on the intercellular Ca 2+ oscillations in an array of bi-directionally coupled cells. It is found that Ca 2+ oscillations may become the most ordered in time when q, τ or N is varied, which characterize the phenomenon of coherence resonance and system size resonance. These results show that the temporal coherence of the Ca 2+ oscillation can be enhanced when the NGN or the cell number is optimal. This work extends the study of the NGN in calcium systems and provides new insight into the roles of the NGN in the intercellular Ca 2+ oscillations in the coupled cells. © 2011 Elsevier B.V. All rights reserved.
Wang D.-H.,Ludong University
Journal of Electromagnetic Waves and Applications | Year: 2014
During photodetachment in external electric and magnetic fields, the detached electron wave propagated from the negative ion in different directions may intersect again at a large distance from the negative ion, thus creating an interference pattern in the detached electrons current density distributions on a detector plane placed at a certain distance from the negative ion. In this work, we calculate the photodetached electrons current density distributions in perpendicular electric and magnetic fields on the basis of the semi-classical theory. Our results suggest that the electron current density distributions on the detector plane are not only related to the electric and magnetic fields strength, but also related to the electron energy. Under certain conditions, the interference pattern could reach macroscopic dimensions and could be observed in a direct photodetachment microscopy experiment. Our studies may guide the future researches in the wave propagation theory and the photodetachment microscopy of negative ion in the presence of external fields. © 2014 Taylor & Francis.
Wei X.,Ludong University |
Guo L.,Beihang University
International Journal of Robust and Nonlinear Control | Year: 2010
A novel type of control scheme combining the disturbance-observer-based control (DOBC) with H∞ control is proposed for a class of complex continuous models with disturbances. The disturbances are supposed to include two parts. One part in the input channel is generated by an exogenous system with uncertainty, which can represent the harmonic signals with modeling perturbations. The other part is supposed to have the bounded H 2-norm. Parametric uncertainties exist both in concerned plant and in exogenous subsystem. The disturbance observers based on regional pole placement and D-stability theory are designed and integrated with conventional H∞ control laws. The new composite DOBC and H∞ control scheme is applied to complex continuous models for the case with known and unknown nonlinearity, respectively. Then the first type of disturbances can be estimated and rejected, and the second type can be attenuated; simultaneously, the desired dynamic performances can be guaranteed. Simulations for a flight control system are given to demonstrate the effectiveness of the results and compare the proposed results with the previous schemes. Copyright © 2009 John Wiley & Sons, Ltd.
Xu H.,The State University of New York at Potsdam |
Xu H.,Ludong University |
Hepel M.,The State University of New York at Potsdam
Analytical Chemistry | Year: 2011
We report on the development of a fluorescence turn-on "molecular beacon" probe for the detection of glutathione (GSH) and cysteine (Cys). The method is based on a competitive ligation of Hg2+ ions by GSH/Cys and thymine-thymine (T-T) mismatches in a DNA strand of the selfhybridizing beacon strand. The assay relies on the distancedependent optical properties of the fluorophore/quencher pair attached to the ends of the molecular beacon DNA strand. In a very selective coordination of Hg2+ to GSH/Cys, the fluorophore/quencher distance increases concomitantly with the dehybridization and dissociation of the beacon stem T-Hg2+-T due to the extraction of Hg2+ ions. This process results in switching the molecular beacon to the "on" state. The concentration range of the probe is 4-200 nM with the limit of detection (LOD) of 4.1 nM for GSH and 4.2 nM Cys. The probe tested satisfactorily against interference for a range of amino acids including sulfurcontaining methionine. © 2011 American Chemical Society.