Structures and electrochemical characteristics of several kinds of alloys

The structures and the electrochemical characteristics of La0.7-xCexMg0.3Ni2.8Co0.5 (x = 0.1-0.5) alloy, Ti0.25-xZrxV0.35Cr0.1Ni0.3 (x = 0.05-0.15) alloy and AB(3of AB(3)-type alloy, solid solution alloy and non-AB(5)-type alloy, respectively, have been investigated, and the performances of MH-Ni battery in which AB(3

Kinetic characteristics of the interaction between morphine and its antibody by SPR competitive immunoassay

It is impossible for surface plasmon resonance to measure directly the binding kinetics between a low-molecular-weight analyte interacting and its immobilized binding partner. Solution competition method was applied to the kinetic study of the interaction between morphine and its antibody. The affinity constant between the antibody of morphine and morphine-BSA immobilized on the sensor chip was also obtained. The result showed that the affinity of polyclonal antibody is stronger than that of monoclonal antibody. And it also indicated that the protein combined with the analyte affected the binding of antibody to antigen.

Synthesis and electrochemical characteristics of lanthanide complexes with 2-nitro-5,10,15,20-tetraphenylporphyrin and acetylacetonate

Four lanthanide complexes with 2-nitro-5,10,15,20-tetraphenylporphyrin and acetylacetonate were prepared and characterized by elemental analyses, LR, UV-Visible,H-1 NMR, XPS and molar conductance. The redox properties of the lutetium complex with 2-nitro-5,10,15,20-tetraphenylporphyrin and acetylacetonate in dichloromethane were studied by cyclic voltammetry.

Preparation and characteristics of polyimide-TiO2 nanocomposite film

A sol-gel approach has been developed to prepare polyimide-TiO2, hybrid films fi om soluble polyimides and a modified titanium precursor. The rate of the hydrolysis reaction of titanium alkoxide can be controlled by using acetic acid as a modifier. FTIR and XPS indicated that TiO2, particles were well distributed in polyimide matrixes with particle size small per than 60 nm. Polyimide hybrid films having the TiO2, component less than or equal to 10% exhibited high thermal stability, high optical transparency and good mechanical properties and possessed higher dielectric constants than correspondingly polyimides. (C) 2000 Society of Chemical Industry.

Electrocatalytic mechanism for formaldehyde oxidation on the highly dispersed gold microparticles and the surface characteristics of the electrode

Electrocatalytic mechanism for the electrochemical oxidation of formaldehyde (HCHO) on the highly dispersed Au microparticles electrodeposited on the surface of the glass carbon (GC) electrode in the alkaline Na2CO3/NaHCO3 solution and the surface characteristics of the Au microparticle-modified glass carbon (Au/GC) electrode were studied with in situ FTIR spectroscopy, scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the final products of HCHO oxidation is HCOO- at the Au/GC electrode and CO2 at the bulk Au electrode. The difference may be ascribed to the different surface characteristics between the Au/GC electrode and the bulk Au electrode. (C) 1999 Elsevier Science B.V. All rights reserved.

Luminescence characteristics of europium and terbium complexes with 1,10-phenanthroline in-situ synthesized in a silica matrix by a two-step sol-gel process

In-situ synthesis of europium and terbium complexes with 1,10-phenanthroline (phen) in silica matrix by a two-step sol-gel process has been proposed. The formation of europium and terbium complexes with phen in sol-gel derived silica gel were confirmed by the luminescence excitation spectra. The silica gels that contain in-situ synthesized europium and terbium complex exhibit the characteristic emission bands of the rare earth ions. Furthermore. the rare earth ions present longer fluorescence lifetimes than the comparable pure complex powder and the complexes dissolved in ethanol solutions. The luminescence properties of the silica gels codoped with europium (or terbium) and phen were also investigated with respect to the gels doped with europium (or terbium). (C) 1999 Elsevier Science B.V. All rights reserved.

Characteristics of the conductive polyimide film surfaces induced by ultraviolet laser beam

A conducting layer with the conductivity of 1.2 Omega(-1)cm(-1) stripped in a solvent from KrF-laser-irradiated polyimide thin film is taken as a sample to determine the microstructure of the conducting layer. Fourier-transform infrared and X-ray photoelectron spectroscopies show the formation of the carbon-rich clusters after irradiation. The element analysis gives the atomic ratio of C:H:N:O for the carbon-rich cluster as 60:20:3:1. Wide-angle X-ray diffraction indicates that the conducting layer is mainly amorphous carbon with a small amount of the short-range ordered carbon-rich clusters. This study suggests a structural model with three-layer carbon sheets linked together in a random fashion for the short-range ordered carbon-rich clusters. The interplanar spacing is 3.87 Angstrom and the layer diameter 25 Angstrom. The transport model of variable-range hopping in three dimensions is used to explain the conducting behavior of the conducting layer. In our case, the short-range ordered carbon-rich clusters are assumed to be conducting islands dispersed in the amorphous carbon-rich cluster matrix.

Mechanical and structural characteristics of phenolphthalein poly(ether sulfone) ultra-high molecular weight polyethylene blends

Mechanical and structural properties of blends of phenolphthalein poly(ether sulfone) (PBS-C) with ultra-high molecular weight polyethylene (UHMWPE) were investigated using tensile and bending testing, scanning electron microscopy and transition electron microscopy. The incorporation of minor amounts of UHMWPE (2 wt.-%) into PES-C has a reinforcement effect. With higher concentrations of UHMWPE, the mechanical properties decrease gradually. Structural studies demonstrated that the blends are multiphasic in the whole composition range. The minor UHMWPE, dispersed uniformly and oriented along the flow direction, as well as the strong interfacial adhesion contribute to the increase of the mechanical performance of the blends. The domain size of the UHMWPE phase was found to increase with the increase of its concentration.

Interfacial characteristics of the self-assembly system of poly-L-lysine 3-mercaptopropionic acid gold electrode

The interfacial characteristics of poly-L-lysine (PL) attached on self-assembled monolayers (SAMs) of 3-mercaptopropionic acid (MPA) were studied by an electrochemical method. The results indicated that PL\MPA layer inhibited partly the diffusion process of redox species in solution, and the electrode surface behaved like a microelectrode array. Its permeation effect was also strongly affected by Mg2+. The more Mg2+ ions were added into the electrolyte solution, the greater the difficulty with which the electron transfer of potassium ferricyanide took place. The three different conformations of PL on the electrode surface had different influences on the electron transfer processes of ferricyanide. PL in random coil state hindered most strongly the electron transfer behavior of ferricyanide,while the alpha-helical PL had nearly no effect and the effect of the beta-sheet state PL was intermediate of these. (C) 1997 Elsevier Science S.A.

Synthesis and luminescence characteristics of LiMgAlF6:Ln(3+) (Ln = Ce, Eu, Tb)

By solid state reaction, LiMgAlF6 and LiMgAlF6:Ln(3+) are synthetized with the ratio 120/100/110 of LiF/MgF2/AlF3, at 1008 K, in high-purity Ar stream. Their crystal structure which belongs to hexagonal system are determined by X-Ray-Diffraction (XRD). Luminescence characteristics of Ce3+, Eu3+, Tb3+ and sensitization of Ce3+ to Tb3+ in LiMgAlF6 are studied. It is shown that the sensitization of Ce3+ to Tb3+ is efficient and a bright green emission is observed.

Electrochemical study of the interfacial characteristics of redox-active viologen thiol self-assembled monolayers

The electrochemical behavior of the electroactive self-assembled monolayers (SAMs) of thiol-functionalized viologen, CH3(CH2)(9)V2+(CH2)(8)SH, where V2+ is a viologen group, on the gold electrodes is examined by cyclic voltammetry and electrochemical a.c. impedance. A monolayer of viologen is immobilized on the gold electrode surface via the Au-S bond and the normal potentials corresponding to the two successive one-electron transfer processes of the viologen active centers are -310 mV and -652 mV (vs. Ag/AgCl) in 0.1 mol l(-1) phosphate buffer solution (pH 6.96) respectively. These results suggest that the viologen SAMs are stable and well-behaved monolayers. The experimental impedance data corresponding to different forms of viologen group have been fitted to equivalent electrical circuits, and the surface capacitances and resistances have been given. The heterogenous electron transfer rates of the first and the second redox processes are 7.57 s(-1) and 1.49 s(-1) respectively through a.c. impedance.

A study of the electrochemical characteristics of the Co(salen)-Nafion modified electrode

A Co(salen)-Nafion modified electrode was prepared by immersing a glassy carbon electrode coated with the Nafion film into the aqueous solution with saturated Co(salen), The modified electrode showed a stable electrochemical reaction of Co(salen) at about 0 V(vs, SCE), The result of XPS indicated the valence of cobalt in Co(salen) changes from +2 before to +3 after Co(salen) enters the Nafion film, It is due to forming axis coordination of cobalt with sulfonic group in Nafion film, It was found that the mode of electron transfer in Co(salen)-Nafion modified electrode was controlled by physical diffusion and electron hopping, It was also found that the modified electrode could catalyze the reduction of O-2 to H2O2. The real catalyst may be the adduct of Co-I(salen) and O-2.

Research on modified electrode of conducting polymer .2. Characteristics of polypyrrole film doped with heteropolyanions

Polypyrrole film electrode with Co(W2O7)(6)(10-) and CuW12O406- ions were synthesised in aqueous solutions, The electrode possesses a good stability and cyclic voltammetric behavior in weakly acidic or near neutral solutions, The redox of CuW12O406- ion can be catalysed by the polypyrrole film, The ESR measurement of the polypyrrole film with Co(W2O7)(6)(10-) and CuW12O406- ions indicates that the heteropolyanions not only play the role of neutralizing electricity in the polypyrrole film, contrasted with the film containing NO3-, but also Interact with the polypyrrole molecular chain to form some additive compound, The additive compound affects the electric structure elf the polypyrrole film and is unstable at more positive or more negative potentials.

SPECTRAL CHARACTERISTICS OF ER3+-ACTIVATED AND CE3+-SENSITIZED YTTRIUM-ALUMINUM-GARNET LASER CRYSTALS

We report in this paper the spectral characteristics of Er3+ (2 at.%)-activated and Ce3+ (0.3 at.%)-sensitized yttrium aluminium garnet (YAG:Er,Ce) laser crystals grown by the Czochralski technique. The absorption and emission spectra were measured at room temperature. By using absorption spectra and Judd-Ofelt theory the experimental oscillator strengths of the Er3+ transitions in the YAG:Er,Ce crystals were calculated. The energy transfer between the Er3+ and Ce3+ ions is also discussed.

SYNTHESIS AND SPECTRAL CHARACTERISTICS OF DIVALENT SAMARIUM ACTIVATED BINARY FLUORIDES

A simple technique for preparation of powder binary fluorides activated with divalent samarium ions is described. The samarium impurity is introduced as samarium trifluoride SmF3 and hydrogen acts as the reducing agent to transform Sm3+ into Sm2+. Using this method, samarium has been stabilized in the divalent state in some fluorides: KMgF3, LiBaF3, BaBeF4, SrMgF4 and BaMgF4. Moreover, BaBeF4, SrMgF4 and BaMgF4 have never been activated with Sm2+ ions up to now. We also find that under the same synthetic conditions samarium can not be stabilized in the divalent state in some fluorides: KCaF3, CaBeF4 and CaMgF4, but the characteristic luminescence of trivalent samarium Sm3+ appears in these matrices. The emission and excitation spectra of samarium (Sm2+ and Sm3+) in these binary fluorides are presented and briefly discussed. The relationship between the oxidation state of samarium and the composition, the structure of matrices is also analyzed.