A contribution to the understanding of a.c. anodizing of aluminium

Commercial aluminium has been anodized in 10% v/v sulphuric acid using alternating current. At 20 V no significant differences in colour and thickness between specimens anodized at the neutral and live terminals were detected. At higher voltages the oxide on the neutral specimens was always more yellow and thinner than that on the live specimens. The colouration was attributed to the reduction of sulphate to sulphide during the cathodic half-cycle, no other sulphur-containing species being detected by XPS. EPMA has shown that the total sulphur distribution across the film was practically uniform and independent of the operating conditions, except in thin films, where it was greatest at the free surface. With additions of ferric sulphate to the solution the reduction to sulphide was inhibited and the differences between live and neutral specimens were avoided. The total amount of sulphur remained unchanged at approximately 5% weight and no iron was incorporated in the film.     

A survey of the microbiological quality of bottled water sold in the UK and changes occurring during storage.

Eight brands of domestic and imported bottled water were microbiologically analysed within three hours of purchase at a local supermarket. Viable numbers of microorganisms were estimated on Plate Count Agar (PCA) and PCA diluted to quarter and tenth strengths (1/4 PCA and 1/10 PCA) and incubated at temperatures of 10, 15, 25 and 37 degrees C. Plate count agar diluted to 1/4 and 1/10 incubated at 25 degrees C yielded the highest initial counts, up to 10(4) cfu ml(-1). Pseudomonas spp. was the predominant species. After 6 months of storage at room temperature (18-25 degrees C), few quantitative and qualitative differences were found in the microflora.     

Comparison of the effects of different types of soya milk on the total antioxidant capacity of black tea infusions

Experimental evidence has shown that the polyphenols in black tea exhibit strong antioxidant potential in vitro and in vivo. The objective of the present study was to analyse and compare the total antioxidant capacity (TAC) of five brands of tea and to evaluate whether the addition of different varieties of soya milk decreased the TAC compared to semi-skimmed bovine milk. Each of the teas analysed was a significant source of antioxidants (7796–10,434 μmol/l FRAP). The addition of milk lowered the TAC of each of the teas analysed. When compared to tea with semi-skimmed bovine milk, each of the five teas analysed had either significantly higher antioxidant values or no change after the addition of soya milk. The addition of soya milk to black tea may be a useful alternative to semi-skimmed bovine milk if wishing to maintain the overall antioxidant potential of the tea infusion.     

A Technique for Totally Automated Audiometry

A means of combining two older audiometric techniques to yield a totally automated determination of hearing threshold levels using an integral audiometer?digital microprocessor is discussed. The design of the audiometric computer is briefly outlined.