Shen Panwen

Structural studies on metal-serum albumin. IV. The interaction of Zn(II), Cd(II) and Hg(II) with HSA and BSA

Abstract There have been no detailed and reliable studies on the environment and configuration of Zn(II), Cd(II) and Hg(II) in the metal centers of human serum albumin and bovine serum albumin to date. In this paper the authentic evidence for the involvement of the cystinyl sulfur atoms in the ligation to the zinc group ions has been obtained from the X-ray photoelectron spectra. The belief that each of the zinc group ions possesses several similar binding sites in human- and bovine serum albumin and is bound to the deprotonated thiol group (-RS − ) of the cysteinyl residues to form tetrahedral and linear metal centers has been further confirmed by the treatment of ligand to metal charge transfer data with Jorgensens method. According to these results, we have inferred that these binding sites may be located at the seventeen disuifide bridges, most likely at the seven pairs of adjacent disulfide bridges between positions 75 and 567, in the serum albumins.

Surface analysis of a TiNiB hydrogen storage electrode

Abstract A TiNiB hydrogen storage alloy electrode was prepared by powder metallurgy. Using X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES), the chemical state and composition of the electrode surface were analysed before and after electrochemical charge-discharge cycles. The constituent elements on the surface existed as oxides or hydroxides. Titanium and boron segregated to the surface, especially boron. At a depth of about 300 A, the alloy bulk concentration was reached. The oxidized surface layer became thicker and the segregation of titanium and boron to the surface gradually increased during cycling. The preferential segregation to the surface was probably induced by chemical reaction. The oxidation and segregation of titanium were main reasons leading to the decrease in capacity of the electrode.

Characteristics of titanium-based C14-type Laves phase alloys and their hydride electrodes

Abstract The pressure-composition-temperature (PCT) isotherms, lattice parameters and electrode properties of titanium-based Laves phase alloys with various compositions were studied in this work. The as-cast pseudobinary Ti 1-x Zr x Fe 0.15 Mn 1.21-y V 0.64 Ni y alloys ( x = 0–0.2, y = 0–0.6) were found to have the same crystal structure of the C14-type Laves phase by analysis of X-ray diffraction patterns. The equilibrium characteristics of their hydrides obtained by measuring PCT isotherms at 30 °C were attributed to both geometric and electronic factors. The electrode properties of the hydrides were dependent on both the plateau pressure of the PCT curves and the electrocatalytic activity of their alloys.

Characteristics of the stoichiometric and non-stoichiometric Laves phase alloys and their hydride electrodes

The pressure-composition isotherms, lattice parameters and electrode properties of the stoichiometric and non-stoichiometric C14 Laves phase alloys with various compositions were studied in this work. The flatness of the plateau pressure of the stoichiometric alloys with vanadium was inferior; however the flatness of the non-stoichiometric alloys on adding manganese improved for the Ti1−xZrxFe0.15Mn0.21+yV0.64Ni1.0 (x = 0.2–0.4, y = 0–0.4) system. The changes in the hydrogen plateau pressure and flatness of the plateau pressure were attributed to the geometric factor and affinity of environmental elements of the tetrahedral interstices hydrogen occupation. The electrode properties of all alloys studied were dependent on the hydrogen plateau pressure and flatness of the plateau pressure of the alloy.

Kinetics of hydrogen absorption-desorption in chemically prepared MnNi5

Abstract The cerium-free MmNi 5 (Mm: mischmetal) alloy was prepared by coprecipitation-reduction method. The prepared alloy has different surface composition from, broader homogeneity range and higher activity than those of metallurgically prepared alloy. The measured sorption rates (absorption and desorption) are more rapid than those of corresponding metallurgically prepared alloy. The apparent activation energies of absorption and desorption in the initial stage are determined to be 5.23 and 16.95 kJ/mole-H 2 respectively. The resulting amounts of hydrogen absorbed could be fitted to a straight line by plotting the amounts of hydrogen vs time or pressure logarithmically. The result leads to the conclusion that the rate of absorption is controlled by the process of surface and then bulk. The rate-controlling step of desorption appears to be bulk diffusion.

THE CHEMICAL SYNTHESIS OF INTERMETALLIC COMPOUNDS AND THEIR HYDROGEN STORAGE PROPERTIES

Hydrogen storage intermetallic compounds TiFe and MmNi5 (Mm: mischmetal) were prepared by chemical method and the properties of these alloys were characterized. The alloys we thus prepared are activated easily. The kinetics of hydrogen absorption of well-activated MmNi5 in the α phase were investigated in detail. According to the dependence of hydrogen content on pressure, the rate-controlling step of hydrogen absorption is believed to be surface-controlled in the α phase. The rate of raction can be expressed as:dn/dt=Ke−E/RT.P/t

Mg-BASED HYDROGEN STORAGE MATERIALS: REPLACEMENT- DIFFUSION METHOD FOR Mg2Ni-XMg AND RELATED HYDROGENATION

ABSTRACT Replacement-Diffusion method is reported to prepare, Mg2Ni-XMg alloys(I). A comparative study of the action of hydrogen has been carried out on (I) and another samples (II) which prepared by metal-lugical method as reported in the literature, a three times faster hydrogenation of (I) compared with (II), and the hydriding rated of (I) can be measured without pre-activation by hydriding-dehydriding process. Thermoanalysis, X-Ray analysis and Pressure-Composition isotherms carried out on (I) show that the amount of Mg2Ni in the alloy as small as 0.23%(by wt.), the hydrogenation occured as usual and the main product is MgH2 in addition to small amount of Mg2NiH4.