Multilayer hydrous oxide growth on copper in base and its correlation with previously reported electrocatalytic data for this electrode system

A repetitive potential cycling procedure was used to produce a specific multilayer hydrous oxide film on copper in base at 60 °C. Such a deposit undergoes reduction in a quasi-reversible manner at ca. −0.1 V (RHE), i.e. at a potential that is unrelated to Pourbaix data for copper but, as demonstrated previously, is of major significance with regard to the electrocatalytic behaviour of this electrode system. In accordance with the incipient hydrous oxide/adatom mediator model of electrocatalysis, an active surface state of the metal (Cu*) is assumed to be involved both in electrocatalysis and as a primary product in the hydrous oxide reduction reaction. While the latter process occurs very rapidly at −0.1 V, it is not usually reversible as it is accompanied by subsequent rapid loss of the active state of the metal. The same general approach was used previously to explain the hydrous oxide and electrocatalytic behaviour of a range of noble metals. Received: 28 August 1999 / Accepted: 11 November 1999     

Redox behaviour of thermally activated platinum electrodes with particular reference to operation at elevated temperature

The present work is a continuation of an earlier investigation of the effect of severe thermal pretreatment on the redox properties of platinum electrodes in aqueous media. The most interesting observation was that raising the solution temperature to ca. 75 °C resulted in a dramatic anodic response in the positive sweep at ca. 0.25 V (RHE). Such behaviour was noted earlier at room temperature but only when the thermally pretreated sample was further activated by cathodic polarization. This transition at 0.25 V was partially reversed on the negative sweep, but the cathodic process involved was subject to severe inhibition. There is independent evidence for similar behaviour for gold in aqueous acid solution. The relevance of the present results to the operation of fuel cell anodes is outlined. Received: 2 December 1999 / Accepted: 24 February 2000     

Multiple-surface testing by a wavelength-scanning interferometer for refractive index inhomogeneity measurement

Wavelength-scanning interferometers can separate the multiple interference signals generated by several reflecting surfaces in the frequency space. Optical thickness variations of a three-layer object and its top surface shape were measured simultaneously by a wavelength-scanning Fizeau interferometer. An efficient sampling window for the phase detection has been derived that can compensate for the frequency detuning of the interference signal and suppress the cross talk from noise components in other frequencies. From the experimental results, the refractive index variation of a glass plate was calculated with an accuracy of ∼1 ppm, which is equivalent to several tens of nanometers in optical thickness variations. The text was submitted by the authors in English.     

Functional characterizations of certain p-spaces

In this paper we prove that p-spaces and ?ech-complete spaces with G_δ-diagonals can be characterized by a familiar function extension property.     

Ionophore synthesis. An enantioselective route to the left-wing of indanomycin (X- 14547A).

An enantioselective synthesis of the tetrahydropyran “left-wing” ofthe ionophore X-14547A is described, wherein stereoselective 1,2-carbonyl additions and an oxapyronone-to-dihydropyran enolate Claisen rearrangement are key stereocontrol elements.     

Spectrophotometric determination of palladium with 1-thioglycerol and a study of palladium complex formation with four similar thio-organic compounds

A study of the reactivity of five thio-organic compounds with palladium^II ions has been made and one of them, 1-thioglycerol, selected for use as a spectrophotometric reagent for palladium. Its sensitivity is 0.01 μg of palladium/cm² for log I₀/I = 0.001. The sensitivity of the other four compounds is about the same. Beer's law is obeyed over the palladium concentration range of 0.5 to 9 ppm. The effects of pH, order of addition of reagents, temperature and diverse ions have been investigated.     

Relations between coordinate and potential scaling in the high-density limit

Exact relations are derived between scaling to the high-density limit of density functional theory and taking Z to infinity for nondegenerate atoms. Gorling-Levy perturbation results are deduced for hydrogenic densities. The kinetic contribution to the correlation energy is also studied, and estimates given for its value for neutral atoms. Popular approximate functionals are tested against these benchmarks.     

A revised level scheme for 158Tb

Four separate reaction studies have been performed which show how the accepted nuclear level scheme for ¹⁵⁸Tb must be modified. This nuclide is of current interest because of the recent suggestion that its electron-capture decay may yield a means of determining the neutrino mass.     

Aziridine ring expansion sequences : A new synthesis of 2-oxazolidones

β-Chloroamine hydrochlorides, produced stereospecifically and regiospecifically from aziridines with anhydrous hydrogen chloride in ether, are condensed with sodium carbonate in dry DMSO to afford isomerically pure 2-oxazolidinones.