Biomedical subjects

Chi-Chuan Hwang

Publications and source records attributed to Chi-Chuan Hwang.

5 recordsLinked to original sources

PubMed2006

Conformational stability and three-dimensional model of the delta-opioid pharmacophore for the extended antiparallel dimer structure of Met-enkephalin in water.

The conformational stability of the extended antiparallel dimer structure of Met-enkephalin in water was analyzed by examining the hydration structure of enkephalin using molecular dynamics simulations. The result shows that, despite of the hydrophicility of the terminal atoms in the pentapeptide, the main contributor for the stability of the dimer in water is the four intermolecular hydrogen bonds between the Gly(2) and Phe(4) groups. The three-dimensional model of the delta-opioid pharmacophore for this dimer structure was also established. Such a model was demonstrated to match the delta-opioid pharmacophore query derived from the non-peptides SIOM, TAN-67, and OMI perfectly. This result thus strongly supports the assumption that the dimer structure of Met-enkephalin is a possible delta-receptor binding conformation.

Chemistry, Pharmaceutical↗

PubMed2006

Electronic properties of capped, finite-length armchair carbon nanotubes in an electric field.

This study investigates the electronic properties of finite-length armchair carbon nanotubes in an electric field (E) using a single-pi-band tight-binding model. Three different tip configurations are considered, namely, open ends with hydrogen terminations (H-terminations), one end capped with half of C60 fullerene and the other end open with H-terminations, and both ends capped with half of C60 fullerene. In general, the electronic states and energy gaps of low-energy electronic structures are highly sensitive to changes in the direction and magnitude of the applied electric field and to the tip configuration. The present results show that the electric field induces a strong modulation of the state energies and energy gaps of the current nanotubes, changes their energy spacings, and prompts the occurrence of semiconductor-metal transitions (SMTs). It is found that the SMTs occur more frequently as the direction of the electric field approaches the symmetry axis or when its magnitude becomes sufficiently large. The present results also indicate that the Fermi levels and energy gaps of the three nanotubes considered in this study are strongly influenced by the cap configuration. Finally, the convergent decay behavior of the energy gap which is observed as the length of the nanotube is increased is also strongly dependent on the tip configuration.

Journal Article↗

PubMed2006

Generalized projective synchronization of chaotic systems with unknown dead-zone input: observer-based approach.

In this paper we investigate the synchronization problem of drive-response chaotic systems with a scalar coupling signal. By using the scalar transmitted signal from the drive chaotic system, an observer-based response chaotic system with dead-zone nonlinear input is designed. An output feedback control technique is derived to achieve generalized projective synchronization between the drive system and the response system. Furthermore, an adaptive control law is established that guarantees generalized projective synchronization without the knowledge of system nonlinearity, and/or system parameters as well as that of parameters in dead-zone input nonlinearity. Two illustrative examples are given to demonstrate the effectiveness of the proposed synchronization scheme.

Algorithms↗

PubMed2006

Exponential synchronization of a class of neural networks with time-varying delays.

This paper aims to present a synchronization scheme for a class of delayed neural networks, which covers the Hopfield neural networks and cellular neural networks with time-varying delays. A feedback control gain matrix is derived to achieve the exponential synchronization of the drive-response structure of neural networks by using the Lyapunov stability theory, and its exponential synchronization condition can be verified if a certain Hamiltonian matrix with no eigenvalues on the imaginary axis. This condition can avoid solving an algebraic Riccati equation. Both the cellular neural networks and Hopfield neural networks with time-varying delays are given as examples for illustration.

Animals↗

PubMed2006

Globally asymptotic stability of a class of neutral-type neural networks with delays.

Several stability conditions for a class of systems with retarded-type delays are presented in the literature. However, no results have yet been presented for neural networks with neutral-type delays. Accordingly, this correspondence investigates the globally asymptotic stability of a class of neutral-type neural networks with delays. This class of systems includes Hopfield neural networks, cellular neural networks, and Cohen-Grossberg neural networks. Based on the Lyapunov stability method, two delay-independent sufficient stability conditions are derived. These stability conditions are easily checked and can be derived from the connection matrix and the network parameters without the requirement for any assumptions regarding the symmetry of the interconnections. Two illustrative examples are presented to demonstrate the validity of the proposed stability criteria.

Algorithms↗