Time depended inhibition of SPMs Na+ /K+ -ATPase induced by cadmium and lead

In this work, time depended interaction of SPMs Na+ /K+ -ATPase with Cd2+ and Pb2+ by single exposure and in the mixture, was investigated. The possibility to selectively detect these ions on the basis on the rate of their interaction with the protein was studied. The decreasing protein concentration increased the sensibility of Na+ /K+ - ATPase towards both metals. The selectivity was obtained by variation of metalenzyme contact time.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Intermetallics – advanced cathode materials in the electrolytic production of hydrogen

The intermetallics, Ti–Pt, Nb-Pd (80%Nb), Pd-Ta, Nb-Pd (65% Nb), Zr-Pt, Hf2Fe and PtMo3, of transition metals have been investigated as cathode materials for the electrolytic hydrogen evolution in an attempt to increase the electrolytic process efficiency. These materials were compared with conventional cathode, Ni. An significant upgrade of the electrolytic efficiency using intermetallics was achived. The effects of those cathode materials on the process efficiency were discussed in the context of transition metal features that issue from their d-electronic configuration.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Influence of external magnetic field on the electrolytic hydrogen evolution on different cathode materials

The correlation between magnetic properties of cathodic materials on the evolution of hydrogen and the separation factor was found. The cathodes were pure Ni and cathodes with the electrocatalytic coatings of following compositions: Ni-Mo (70- 30%), Ni-V (70-30%), Co-Mo (70-30%) and Fe-Mo (60-40%), on Ni substrate. The electrolyte is standard electrolyte (30% KOH) and electrolyte activated with Co-complex [1].Physical chemistry 2008 : 9th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 200

Microwave assisted electrolysis of alkaline water solution

The effect of microwaves (MW) on the electrolytic process of 6M KOH water solution is investigated in the temperature range from 291 K to 337 K. At lower temperatures, microwaves facilitate electrolytic process, whereas the effect is reversed at higher temperatures.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Energy consumption in the electrolytic evolution of hydrogen with iron-nickel electrodes

The possibilities to reduce energy consumption in the electrolytic hydrogen production using ionic activators added into an alkaline electrolyte have been investigated. Two cathode/anode systems, Fe/Ni and Ni/Fe were investigated. We have found that some activators, like tris-(ethylenediamine)Co(III) chloride complex in combination with the sodium molybdate can reduce energy needs per mass unit of hydrogen produced for more than ten percent in all investigated systems compared to those of non-activated electrolytes. Additionally, iron exhibits some special properties in this view.Physical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Electrochemical characteristics of binary silver alloys in alkaline solution

The electrochemical features, electrode capacity and corrosion stability, of silver alloys with Tl, Pb, P,Sb, Ge and In have been investigated. Compared to silver some silver alloys showed improved silver oxide formation and conductivity. The best effects, i.e., dramatic increases of 150% for formation of oxide, were obtained with small amounts of alloying component: 0.44% Tl or 0.44% Pb. Based on obtained results, those effects could be explained in terms of increase of real electrode surface as a consequence of ingredients oxidation, preceding the silver oxidation. (C) 1999 Elsevier Science S.A. All rights reserved

Electrochemical H/D isotope separation efficiency along a hypo-hyper-d-electronic (Ti-Ni) phase diagram

Intermetallic phases (stable and meta-stable) along the Ti-Ni phase diagram, together with the pure constituents (TI, Ni), have been investigated as cathode materials for separation of hydrogen isotopes (protium and deuterium, HID) by water electrolysis from alkaline solutions. The H/.D separation factors, obtained using these electrodes, were compared with their hydridic and electrocatalytic features significant for the hydrogen evolution reaction (HER), the enthalpies of intermetallic formation, and their electronic work function. As with the similar behavior of transition elements along the Periodic Table, close correlations were found amongst them. The Ti-Ni intermetallic phases obey typical volcanic plots for all the mutually compared properties along their phase diagram. The TiNi3 alloy with an average d(8)-electronic configuration has maximal electrocatalytic activity for both hydrogen evolution and H/D electrochemical separation processes, the highest value of electronic work function, as well as maximal enthalpy of formation. Intermetallic phases Ti2Ni and TiNi, with an average electronic configuration between d(4) and d(5), exhibit lower values on each of these specific curves. The similarity between the mentioned features suggests that the average electronic configuration of these intermetallic phases determine overall electrode process kinetics, isotope separation efficiency, bond strength, electronic work function, and other physical and chemical properties

Hydrogen Storage in Martensite Ti-Zr-Ni Alloy: A Density Functional Theory Study

The hydrogen storage potential of TiNi-based shape memory alloys is an attractive but experimentally challenging issue. We employ the FP (L)APW+lo method, based on the density functional theory (DFT), in order to address the electronic structure of the low-temperature, martensitic phase of Ti0.67Zr0.33Ni and its hydrides. Further, the thermodynamics of hydride formation in the martensitic Ti-Zr-Ni alloys is studied, and some unanswered questions regarding the hydriding of martensite TiNi are resolved. The calculated formation energy of the orthorhombic beta- and gamma-hydrides of martensitic Ti0.67Zr0.33Ni is, respectively, -14.2 kJ/mol(H) and -29.6 kJ/mol(H), showing that isostructural (Ti,Zr)Ni hydrides with a larger amount of titanium have improved potential for hydrogen storage applications. Furthermore, based on the calculation results, it is unlikely that the hydriding of TiNi martensite would lead to the formation of orthorhombic beta-hydride in analogy to the pseudobinary compound. The formation of Ti0.67Zr0.33Ni hydrides leads to significant changes in electronic structure, causing shifting of some metal states to lower energies due to their interaction with hydrogen s states, and the increase of the number of states at Fermi energy. By modeling intermediate structures, the process of hydride formation in martensitic Ti0.67Zr0.33Ni is resolved to reveal the effects of crystal structure change, volume increase, and hydrogen-metal interactions on the band structure, charge transfer, and thermodynamics. A dominant, stabilizing effect in the process of hydride formation was found to come from the chemical interaction of hydrogen and metal atoms

Spectrophotometric study of hexanitrocobaltate(III) ion spontaneous reduction in water-ethanol and water-acetone mixtures

The kinetics of the spontaneous reduction of hexanitrocobaltate(III) ion have been investigated spectrophotometrically (lambda=360 nm at 298 K) in ethanol or acetone water mixtures containing 0, 10, 25 and 50 % of organic solvents. The mechanism of this process was expressed by means of two consecutive first-order reactions. Both of the first-order rate constants decrease with the increasing nonaqueous species content. The reduction of hexanitrocobaltate(III) ion in the mixtures was much slower than the corresponding reaction in water

Investigation of hydrogen absorption kinetics on intermetallic compounds Hf2Ni, Hf2Co and Hf2Fe

Polycrystalline intermetallics Hf2Ni, Hf2Co and Hf2Fe are investigated as the hydrogen absorbers in the temperature range 348 to 823 K, under the constant hydrogen pressure of 1 bar. The absorption process was carried out in typical volumetric apparatus and H/M mole ratios together with rate constants and activation energies for hydrogen absorption reaction were determined. Achieved hydrogen absorption capacities at 573 K are: 0.60, 0.90 and 1.48 and rate constants at 573 K are: 0.38×10-3, 0.55×10-3 and 4.72×10-3 s-1 for Hf2Ni, Hf2Co and Hf2Fe respectively. Determined activation energies are: for Hf2Ni, 38.44 kJ/mol, for Hf2Co, 19.62 kJ/mol and 2.74 kJ/mol for Hf2Fe. From the obtained experimental results, it was concluded that Hf2Fe has the best hydrogen absorption ability among the examined intermetallics