Proton-proton correlations at small relative momentum in neon-nucleus collisions at E/A=400 and 800 MeV

Proton-proton small angle correlations have been measured in neon-nucleus collisions, using the 4 pi detector Diogene, at 400 and 800 MeV per nucleon incident energies. Values of the size of the emitting region are obtained by comparison with the Koonin formula, taking into account the biases of the apparatus. The dependence of the density on target mass and incident energy is also analysed.     

Bioaccumulation and voltammetry of gold at flower-biomass modified electrodes

The bioaccumulation of gold at antheral cells from flower Datura innoxia is investigated by incorporating these plant cells into a carbon paste matrix. The resulting plant-modified electrode offers a preferential uptake of gold from dilute solutions. The voltammetric behavior of the surface-bound gold is examined under different preconcentration conditions. Scanning electron microscopy offers useful insights into the gold collection process. Convenient measurements of micromolar gold concentrations are possible, with effective self cleaning allowing the use of a single electrode in multiple determinations (R.S.D. of 4.8% for 50 repetitions). The sensitivity and selectivity enhancements associated with the preferential bioaccumulation process, and the convenient surface regeneration, offer the prospect of using the flower-biomass containing electrodes as sensors for gold.     

Capillary gas chromatography of hydrocarbon mixtures containing alkanes and alkenes, selective olefin stripping applied to very diluted samples

An original subtraction method was developed to distinguish between alkanes and alkenes in a complex hydrocarbon mixture. The method described is very fast, inexpensive and requires only 100-200 mul of sample. Its steps include bromination of the olefins and adsorption on a silica gel column followed by gas chromatography. Examples are presented to demonstrate the applicability of the method in practice. The results are compared with those obtained from catalytic hydrogenation.