Vector Potential Theory on Nonsmooth Domains in R3 and Applications to Electromagnetic Scattering

We study boundary value problems for the time-harmonic form of the Maxwell equations, as well as for other related systems of equations, on arbitrary Lipschitz domains in the three-dimensional Euclidean space. The main goal is to develop the corresponding theory for L^p-integrable bounday data for optimal values of p’s. We also discuss a number of relevant applications in electromagnetic scattering.     

The development of redox-modified electrodes as charge-accumulating devices for use in higher sensitivity detection systems

Electrochemical methods can be applied in a number of ways as detection systems for competitive immunoassays, especially through the use of redox-labelled antigens. To overcome the problem of detection of such conjugates at low concentration, a system is described in which a poly(vinylferrocene)-modified glassy carbon electrode is used to accumulate charge from solution glucose/glucose oxidase via the intermediacy of a redox-labelled antigen, cycled repeatedly between the enzyme and the electrode. The charge accumulated by the electrode is measured electrochemically by returning the electrode to its original potential and integrating the resulting current-time transient. The charge is proportional to the concentration of redox-labelled antigen in solution and to the charge-accumulation time. In this way 1,1'-dimethylferrocene-ethan-1-ol-2-amine was reproducibly detected to 0.9 nM, with a 10 min incubation period. The 8-ferrocenyl conjugate of theophylline was characterised as a model system for possible application in a higher sensitivity electrochemical immunoassay.     

A probe of the relative rate of interconversion of carbonium ion conformers vs proton loss in 9-hydroxy-10-methyldecahydronaphthalenes

Deutero-alcohol (2b) was prepared and dehydrated with H₂SO₄Ac₂OHOAc to give a kinetic isotope effect demonstrating anion mobility within the intermediate carbocation-anion ion pair.     

Determination of the stereochemistry of anhydroerythromycin A, the principal degradation product of the antibiotic erythromycin A

Anhydroerythromycin A arises from the acid-catalysed degradation of erythromycin A both in vitro and in vivo. It has negligible antibacterial activity, but inhibits drug oxidation in the liver, and is responsible for unwanted drug-drug interactions. Its structure has 18 chiral centres common with erythromycin A, but C-9 (the spiro carbon) is also chiral in anhydroerythromycin and its stereochemistry has not previously been reported; both 9R- and 9S-anhydroerythromycin A are plausible structures. An understanding of the chirality at C-9 was expected to throw light on the mechanism of acid-catalysed degradation of erythromycin A, a subject that has been debated in the literature over several decades.We now report a determination of the three-dimensional structure of anhydroerythromycin A, including the stereochemistry at C-9, by NMR and molecular modelling. In parallel, the relative stereochemistry of anhydroerythromycin A 2'-acetate was determined by X-ray crystallography. Both compounds were shown to have 9R stereochemistry, and anhydroerythromycin A exhibited considerable conformational flexibility in solution.     

Mathematics learning support and engagement in first year engineering

This paper considers the effects of both free optional mathematics learning support and engagement on the mathematics performance in a foundation mathematics subject of a cohort of engineering students entering university with poor mathematical skills. New engineering students were directed to either a foundation or standard mathematics subject based on the results of a placement test. For students in the foundation subject, it was found that high levels of learning support were associated with greater improvement over the semester. Some form of learning support was used by 57.9% of the students, a reasonably high proportion of the cohort. Some factors for this high level of use of learning support are considered. One possible factor, the placement test, appears to have had a positive effect. Engagement in the subject activities as measured by tutorial attendance and learning management system use was found to have a positive association with final mark. Students who utilized a high level of learning support were more likely to be more engaged with the subject, making it impossible to draw conclusions about improvements being solely due to the use of learning support.