A chemical catalytic method for determination of silver in human saliva.
Abstract A catalytic method for the determination of silver in saliva is suggested. Silver was determined by a very simple technique in concentrations in saliva higher than 1 μg/100 ml with a coefficient of variation of 5.7 per cent. The method was used to investigate the correlation between some pathogalvanic phenomena connected with the presence of amalgam restorations in the oral cavity and the concentration of silver in saliva. The application of the method showed no correlation between the number of restorations and the silver concentration in saliva. The joint effects of restorations, their corrosion potential and the concentration of silver in saliva were correlated with the occurrence of unpleasant sensations in the mouth.
Catalytic activity and complexation-iv 2,2'-Bipyridyl as activator for the catalytic ultramicro determination of silver.
The activation of the catalytic persulphate oxidation of sulphanilic acid when the catalyst, silver(I), is suitably complexed, is discussed. 2,2'-Bipyridyl is proposed as activator as it accelerates the rate-determining step of the process-the oxidation of silver(I) to silver(II). The mechanism of activation is investigated and discussed in detail. On the basis of these investigations a catalytic method has been developed for the determination of silver(I), with a sensitivity of 4 x 10(-4)mug ml and +/-7.6% relative error.
Unidirectional hexagonal rare-earth disilicide nanowires on vicinal Si(100)-2×1
Rare-earth disilicide nanowires grown on vicinal Si(100) with a miscut of 2–2.5° toward the [110] azimuth at 600 °C were studied by scanning tunneling microscopy and compared with those grown on flat Si(001). In contrast to rare-earth disilicide nanowires grown on flat Si(100) surfaces, the nanowires grow unidirectionally along the [01̄1] direction of the vicinal Si(100) surface. Rare-earth disilicide nanowires form bundles composed of single nanowire units on both flat and vicinal surfaces. Yet, on the vicinal surface, the bundle width is comparable to the width of the terrace. The average nanowire length on the vicinal substrate is longer than that on the flat substrate. Scanning tunneling spectroscopy shows that the rare-earth disilicide nanowires have metallic properties.