Measurement of the Rates of Diffusion of Halomethanes into Polymer Films Using ATR-FTIR Spectroscopy

Polymer-modified attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy and FEWS (fibre-optic evanescent wave) spectroscopy have been very successful to date for sensitive detection of organic pollutants in water utilising the mid-infrared (MIR) region of the electromagnetic spectrum (4000-400 cm^?1). This sensing approach involves the use of different polymer films for preconcentration with optimisation of the sensor related to the rate of diffusion of solvent molecules into these polymer films. Compounds such as chloroform, bromoform, bromodichloromethane and dibromochloromethane which are collectively referred to as trihalomethanes (THMs) were analysed in this work. A gaseous phase experimental design was used and from experimental data the rate of diffusion of each of the halomethanes was quantified based on a Fickian type diffusion model. Individual diffusion coefficient values were found to be in the range 3.38 E-10 ± 0.01 E-10 to 4.72 E-08 ± 0.42 E-08 cm² s^?1. Multicomponent effects were observed for mixtures of compounds diffusing into polyisobutylene and ethylene-propylene copolymer.     

The selectivity of electrosynthesised polymer membranes depends on the electrode dimensions: implications for biosensor applications

A biosensor selectivity coefficient defined for poly(o-phenylenediamine) electrosynthesised onto Pt microdisks and cylinders was unexpectedly found to change as the scale of the electrodes decreased, mainly due to enhanced permeability of a ubiquitous interference species in biological systems, ascorbic acid.     

Electrochemical genosensor based on three-dimensional DNA polymer brushes monolayers

A new approach to the three dimensional integration of short DNA strands at gold electrode surfaces via the in situ formation of DNA-acrylamide conjugates is presented. Surface initiated atom transfer radical polymerisation was employed to grow acrylamide brushes co-polymerised in the presence of acrylamide modified DNA probes. This strategy was demonstrated for the realisation of biofunctionalised thin polymer films capable of binding its complementary 105-base DNA amplicon. The synthesised brushes were characterised using atomic force microscopy, attenuated total reflectance spectroscopy and electrochemical impedance spectroscopy. Once characterised, the polymer brushes were applied to the quantitative detection of target DNA using an enzyme labelled reporter DNA probe in a sandwich-type format.     

Synthetic mimicking of plant oils and comparison with naturally grown products in polyurethane synthesis

The use of plant oils as industrial feedstocks can often be hampered by their lack of optimization towards a particular process, as well as their development being risky; growing suitable volumes of crops to test can take up to five years. To circumvent this, we aimed to discover a method that would mimic plant oil profiles in the laboratory, and show that they exhibited similar properties to the naturally grown plant oils in a given process. Using the synthesis of polyurethanes as an example, we have synthesized six different polymers and demonstrated that plant oils will produce polymers with similar physical properties to those oils mimicked in the laboratory. The use of this mimicking process can be extended to other types of polymers to obtain a method for predicting the properties of a given material based on the plant oil composition of a crop before it is grown in bulk.     

Yang-Mills theory and Tamagawa numbers: the fascination of unexpected links in mathematics

Atiyah and Bott used equivariant Morse theory applied to theYang–Mills functional to calculate the Betti numbers ofmoduli spaces of vector bundles over a Riemann surface, rederivinginductive formulae obtained from an arithmetic approach whichinvolved the Tamagawa number of SL_n. This article attempts tosurvey and extend our understanding of this link between Yang–Millstheory and Tamagawa numbers, and to explain how methods usedover the last three decades to study the singular cohomologyof moduli spaces of bundles on a smooth projective curve over can be adapted to the setting of ¹-homotopy theory to studythe motivic cohomology of these moduli spaces over an algebraicallyclosed field.