Papers by Keyword: Covalent Bonding

Abstract: We have performed First-principles density functional calculation by using full potential linearized augmented plane wave (FP-LAPW) method within generalized gradient approximation (GGA) of B₂- AlGd (Aluminum compound). The ground state properties along with electronic and elastic properties are studied. The energy ranges are given for bands which are crossing the Fermi level and explained whether the Fermi surface is formed by hole pocket or electron pocket. Bonding properties are analyzed by charge density plot. By B/G_H ratio the brittleness of the material is determined.

Abstract: In this paper we present bond-order potentials (BOPs) based on the tight-binding method. The potentials have been developed for bcc non-magnetic metals of group V.B (V, Nb, Ta) and group VI.B (Cr, Mo, W) as well as for the ferromagnetic bcc iron. The testing of the transferability of BOPs involves energies of alternate structures, formation energies of vacancies and self-interstitials, transformation paths between different structures and phonon dispersion relations. An example of the application of these potentials is modeling of the structure and glide of 1⁄2<111> screw dislocations under the effect of applied shear and tensile/compressive stresses.

Abstract: In order to prepare the enzyme electrode for sensing of chemical molecules, the Au was coated on the surface of PP film by sputter coater. Polyaniline (PANI) was polymerized on the surface of the coated Au film by electrochemical polymerization of aniline in order to use working electrode. Subsequently, horseradish peroxide (HRP) was immobilized on PANI electrode as follows: Method I. The HRP was immobilized on the surface of PANI electrode by using Au nanoparticle as linker (physical adsorption). Method II. The HRP was immobilized on the surface of PANI electrode by using 2-aminothiophenol and Au nanoparticle as linker (Self-assembling immobilization). Method III. HRP was directly immobilized with PANI electrode by using glutaric dialdehyde as linker (covalent bonding). The sensing efficiency of the prepared HRP-PANI electrode was also examined. The sensing efficiency of the HRP-PANI electrode for H2O2 was as following order; Method I > Method III > Method II..

Abstract: Hydroxyapatite (HAp) has unique properties for biomaterials such as hard-tissue-compatible material for bone and tooth and also soft-tissue-compatible materials for skin tissue. However, the hard and brittle nature of HAp limits spreading many medical devices. Recently, a unique composite of sintered HAp nano-crystals -- ceramics -- covalently coupled to polymer substrates was developed -- Nano-Ceramic Coating --. The development was depended on the two original technologies: (1) control of size/morphology of high-dispersed sintered nano-HAp, (2) donation of covalent bonding between nano-HAp and substrates to coat strongly on the surface. The nano-composite material holds not only the mechanical properties of the substrate but also biological properties of the ceramics coated on the surface. In this report, the method of synthesis of high-dispersed nano-HAp, the preparation of the nano-composite, the biological properties with cells or animal tissue, and especially, the development of medical devices, such as percutaneous device or blood vessel and so on, made of the composite will be presented.