Biomedical subjects

Gareth J Price

Publications and source records attributed to Gareth J Price.

4 recordsLinked to original sources

PubMed2003

Recent developments in sonochemical polymerisation.

High intensity ultrasound has been applied to two classes of step-growth polymerisation. The ring-opening polymerisation of cyclic lactones to polyesters was accelerated under 20 kHz ultrasound but, in the case of delta-valerolactone, sonication also promoted a depolymerisation reaction so that the molecular weight fell during later stages of the reaction. Sonication was also applied to the preparation of polyurethanes from a number of diisocyanates and diols. In all cases, the sonochemical reactions proceeded faster in the early stages and led to higher molecular weight polymers. The effect of changing the ultrasound intensity is discussed and some speculation as to the mechanisms of the reaction enhancements is given.

Journal Article↗

PubMed2002

Applications of inverse gas chromatography in the study of liquid crystalline stationary phases.

We describe measurements on a number of low-molar-mass and polymeric liquid crystals that contain the same mesogenic groups. Transition temperatures for the mesophases have been measured and the supercooled region of hexyloxycyanobiphenyl studied, revealing some differences from the stable mesophase. Activity coefficients and interaction parameters for a range of probes have been measured and allow us to determine the nature and origin of the thermodynamic interactions in the systems. A discussion of how this fundamental information can be used in designing more efficient stationary phases for analytical gas chromatography is also presented.

Chromatography, Gas↗

PubMed2002

Sonoluminescence quenching by organic acids in aqueous solution: pH and frequency effects.

The quenching of sonoluminescence from aqueous solutions by acrylic and methacrylic acids is dependent on whether the acid is ionised in solution, as controlled by the pH, but also by the frequency of ultrasound used.

Journal Article↗

PubMed2002

Inverse gas chromatographic measurement of solubility parameters in liquid crystalline systems.

Inverse gas chromatography, (IGC), has been used to measure interaction parameters in two low-molar-mass liquid crystals and a polymer substituted with the same mesogenic group. Solubility parameters have been calculated. The IGC method is shown to be applicable to this class of compounds and to give meaningful values over a range of temperatures.

Chromatography, Gas↗