Ian Thompson

Real-time confocal imaging, during active air abrasion – substrate cutting

Air abrasion cutting, using particulates accelerated in a controlled compressed gas stream, is currently being re‐evaluated as a precision tissue removal technique for dental cavity preparation. The minimal vibrations and heat generated during cutting commend the technique for use in the shaping of fragile or brittle materials that are vulnerable to vibrations and thermal stresses.

Prospective cohort comparison of bioactive glass implants and conchal cartilage in reconstruction of the posterior canal wall during tympanomastoidectomy

Objective:u2002 To compare the effectiveness of bioactive glass implants and conchal cartilage in reconstructing the posterior canal wall during tympanomastoidectomy.

Synthesis of nucleic-acid base containing norbornene derivatives as monomers for ring-opening-metathesis-polymerization

A series of norbornene derivatives containing nucleic-acid bases (thymine, adenine, cytosine, guanine, or uracil) have been prepared as monomers for ring-opening-metathesis–polymerization (ROMP). Many of the initially prepared monomers had poor solubility but this could be overcome by appropriate choice of a linker between the norbornene and base units. Some of the monomers were successfully polymerised to give homopolymers derived from nucleic-acid bases.

The mechanism of formation of 8,8-dimethyl[4.2.1.03,7]nonan-6-yl acetate (fortesyl acetate) during acetolysis of nopyl toluene-p-sulfonate

Attempts to prepare 2-(2-hydroxyethyl)-6,6-dimethylbicyclo[3.1.1]hept-2-ene (nopol; 1) labelled with deuterium at C-10 by a process of oxidation of the primary alcohol group of nopol to the aldehyde, followed by H/D exchange and reduction back to alcohol, were unsuccessful because various oxidation procedures, including reaction with N-chlorosuccinimide at –78xa0°C, gave instead a carboxylic acid having an oxygen at C-3. Nopol, labelled at C-11 with deuterium, was obtained through a Prins reaction of β-pinene with deuteriated paraformaldehyde. This labelled nopol was converted into its toluene-p-sulfonate ester, and was solvolysed in acetic acid containing acetate ion to give 8,8-dimethyltricyclo[4.2.1.03,7]nonan-6-yl acetate, which is an earlier reported novel fused ring system (fortesyl acetate; 2 acetate). The position of the label in the product showed that the mechanism of this deep-seated carbon skeletal rearrangement proceeds through the intermediate formation of a cyclobutane ring, followed by shift of a methylene bridge to expand the original cyclobutane ring and then subsequent expansion of the new cyclobutane ring. Calculations of heats of formation of possible ions involved in these shifts confirm the proposed mechanism as the most likely pathway.