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A non-conforming apparatus was devised to study the wear properties of hip replacement materials (stainless steel femoral head and mainly ultra-high molecular weight polyethylene, UHMWPE). The analysis was by wear depth and various types of microscope examination of the worn surfaces. The importance of proper femoral head surface conditions is emphasized. The dry worn debris matched that retrieved from revision surgery indicating the in vivo wear was without fluid lubrication. A qualitative model is presented to explain the observed wear and wear rate profiles. The long-term wear was within a narrow range that matched in vivo results. Tests on polyetherether ketone (PEEK) polymer indicated that it had superior wear properties to UHMWPE.

The electrocatalytic hydrogenation of 4-(4-hydroxyphenyl)buten-2-one at a nickel cathode in aqueous ethanol containing sulphuric acid has been examined. HPLC was used for the analysis of reaction mixtures. The product composition is critically dependent on the method used for electrodeposition of the nickel-black surface. An electrochemically deposited nickel-black will catalyse the electrochemical hydrogenation of this substrate. Formation of 4-(4-hydroxyphenyl)butan-2-one is favoured at high concentrations of substrate and a minor amount of the corresponding secondary alcohol is also formed. The process was applied also to hydrogenation of 4-(4-methoxyphenyl)buten-2-one and 4-(4-hydroxy-3-methoxy-phenyl)buten-2-one with 63–68% current efficiency. An alternative process, the reduction of these enones at a lead cathode in presence of sodium hydrogen carbonate, gave an unsatisfactory mixture of products.

One electron reduction of aryl halides is known to generate the aryl radical and halide ion. These aryl radicals will cyclize onto an adjacent benzene ring in a reaction that is potentially useful in organic synthesis and which is well documented at a mercury cathode. 5-(2-Halophenyl)-1-(4-fluorophenyl)tetrazoles are used here as representative substrates and the cyclization reaction to 7-fluorotetrazolo[1,5-f]phenanthridine is developed at cathodes of cadmium, zinc and mild-steel. A high yield of the desired cyclization product is achieved using a mild-steel cathode and a sacrificial magnesium anode in an undivided cell with acetonitrile, 0.1 M tetraethyl ammonium tetrafluoroborate as electrolyte and under an air atmosphere.

The synthesis and electropolymerization of 2-[2-(1-pyrrolyl)ethylamino]-3-chloronaphthoquinone (PNQ) and 2,5-bis[2-(1-pyrrolyl)ethylamino]-2,6-dichlorobenzoquinone (PBQ). are described. Electrochemical behaviour of poly(PNQ) and poly(PBQ) films on platinum electrodes was investigated in acetonitrile media. A stable composite film was obtained by the oxidation of PNQ on a polypyrrole coated Pt electrode.

Aqueous carbon dioxide is photochemically reduced in the presence of semiconductor suspensions and colloids. Experiments have been performed using CdS, ZnO, SiC, Ba TiO3, and SrTiO3, dispersions. Product analysis showed the formation of formic acid formaldehyde, sometimes methanol and in the presence of tetramethylammonium chloride, two-carbon products such as glyoxylic and acetic acids and sometimes acetaldehyde. Product yields and photochemical yields were studied as a function of pH, solution composition, added sacrifical electron donors and catalysts, irradiation intensity and irradiation time. A demonstration experiment with a flat-bed solar collector showed the formation of formic acid and formaldehyde using direct sunlight.

Poly(thiophene-benzoquinone) films were prepared on platinum spheres by electropolymerization of the monomer 1-[3-(3-thienyl)propyl]2,4,5-trichloro-3,6-dioxo-1,4-cyclohexadiene-1-acetate (TBQ) in acetonitrile. These films were studied mainly by cyclic voltammetry and chronoamperometry in acetonitrile containing tetraalkylammonium salts as the supporting electrolyte.

Poly(pyrrole-pyromellitimide) films were prepared by the anodic oxidation of N,N'-bis[2-(1-pyrrolyl)ethyl]pyromellitimide (BEP) in acetonitrile media. These films showed a stable redox behaviour in acetonitrile as well as in water media containing 0.1 M tetraalkylammonium salt or LiClO4, as the supporting electrolyte. Poly(BEP) adsorbed a layer of poly(Nϵ-4-nitrobenzoyl-L-lysine) and this bilayer exhibited charging of both electroactive groups.

Non-stoichiometric manganese dioxide prepared electrochemically at room temperature and suspended in dilute sulphuric acid is used to oxidise isosafrole to piperonal in 54% isolated yield. The manganese dioxide-manganese(II) sulphate system can be recycled electrochemically at high current density. It has the further advantage that water-soluble materials derived from the chemical oxidation step can be removed by filtration at the manganese dioxide stage. Direct oxidation of isosafrole at a lead dioxide anode leads to further oxidation of the piperonal.

Redox potentials (vs. sce) have been measured for o - and p -methyl substituted benzophenone, radical anion couples in dimethylformamide and the data interpreted with the aid of previous work of the UV-spectra of benzophenones. The results are explained by the electronic effect of the methyl group and the steric effect of o -groups which increases the average tilt of a phenyl ring with respect to the plane of the carbonyl function. The electronic effect of a p -methyl depends on the average tilt of the phenyl ring.

The rate constant ( k t ) for electron transfer between a donor radicalanion and an acceptor can be determined by electrochemical methods when the so-formed acceptor radicaanion undergoes irreversible fragmentation. When fast bond clevage (rate constant, k r ) occurs within the encounter pair for electron transfer the experimental relationship between log k t and E ° D does not give sufficient information to define the parameters for electron transfer and bond cleavage of the acceptor molecule. The value of E ° A becomes uncertain within a small range. knowledge of k r removes this uncertainty in E ° A .

Poly(pyrrole) has the useful property of forming a tough matrix which moulds to the electrode support. In view of the growing interest in redox materials held on an electrode surface by covalent attachment to poly(pyrrole) [l-6], we were led to examine the redox behaviour of some materials in this class. We report here the behaviour of the 9-cyanoanthracene group in an electrode coating formed by oxidative polymerization of 1-[2-(9-cyanoanthracene-lO-ylmethylamino)ethyl]pyrrole (1). The behaviour of this polymer [poly(l)] on cyclic voltammetry (CV) and chronoamperometry (CA) in the cathodic region, where the 9cyanoanthracene group is electroactive, is strikingly different from the behaviour of most other electroactive polymers.

In order to look for new catalytic routes in the electroreduction of carbon dioxide, the voltammetry of mixed solutions of carbon dioxide and sulphonated phthalocyanines in DMSO has been investigated. An additional reduction wave was observed at more negative potentials than the second (−1.3 V SCE ) phthalcyanine reduction wave, for both copper and nickel phthalocyanines. No additional waves were observed with cobalt phthalocyanine, though shifts were observed in the second phthalocyanine reduction wave for all three phthalocyanines. The additional waves are thought to indicate the formation of a complex between CO 2 and the reduced phthalocyanine ion.

The aqueous voltammetry of Co, Ni, Cu and Zn sulphonated metallophthalocyanines has been examined and compared to the voltammetry in DMSO. In DMSO, Ni, Cu and Zn phthalocyanines exhibit two quasi-reversible, phthalocyanine ligand based, one-electron transfers. Two reduction waves were also observed for Co phthalocyanine. However, the first reduction wave appeared to involve both a metal based electron transfer and a change in the coordination of the metal. The aqueous voltammetry of the cobalt phthalocyanine was similar to its non-aqueous behaviour. The other three phthalocyanines did not show the quasi-reversible behaviour in aqueous solution. Reversibility was much diminished and the forms of the waves changed greatly, indicating the involvement of protons in the redox processes.

Carbon dioxide, in aqueous solution containing tetramethylammonium ions at pH 9 was reduced in two steps to yield oxalic acid at −0.9 V and glyoxylic acid at −1.8 V on carbon and on mercury. Products were analysed by HPLC and confirmed by specific colorimetric measurements.