Version control

Software evolves in small steps or versions. Often these versions are results of collaborations among different persons. At times we want to fall back to a previous version or compare different variants. Or, we need to trace changes to change requests. All these tasks relate to version control and show that tool support in this domain is indispensable, as it is with editors and compilers. The author describes available tools and shows why the CVS open source tool is so popular among practitioners.     

Estrogenic personal care products in a greywater reuse system.

The occurrence and fate of parabens in a greywater system was assessed. The potential for removal of residual paraben concentrations in effluent greywater with chlorine dioxide was also investigated. The influent to the greywater plant was characterised by considerable variation, with concentrations from below the detection limit to 40 microg/L and the five commonly used parabens in consumer products were frequently detected. After the biological treatment only two paraben were detected with concentration from 65-120 ng/L. Chlorine dioxide treatment of the biologically treated effluent with dosages down to 0.75 mg/L resulted in more than 97% reduction of all parabens. Formation of the by-product chloroform was insignificant from the chlorine dioxide treatment.     

Butyltin Species and Inorganic Tin in Water and Sediment of the Detroit and St. Clair Rivers

Water and sediment samples from 29 locations in the Detroit and St. Clair rivers were analyzed for the highly toxic tri-n-butyltin (Bu₃Sn⁺) species and for the less toxic di-n-butyltin (Bu₂Sn²⁺) and n-butyltin (BuSn³⁺) species and inorganic tin. In general, locations sampled in the St. Clair River were less contaminated with butyltin species than those in the Detroit River. Inorganic tin and BuSn³⁺ were detected in over 90% of all subsurface water samples, while Bu₂Sn²⁺ and Bu₃Sn⁺ were detected in 45 and 28% of the same samples, respectively. The highest concentration ofBu₃Sn⁺ in subsurface water, 5.9 × 10^?10 mol Sn/L, was at the mouth of the Ecorse River, a tributary of the Detroit River. The three butyltin species and inorganic tin were also detected in 23–46% of all sediment samples. The highest concentrations of Bu₃Sn⁺ in sediment were found close to the mouths of the River Rouge, another tributary of the Detroit River, and the Ecorse River, and were 6.2 × I0^–7 and 1.7 × I0^–7 mol Sn/kg dry weight, respectively, for the top 2 cm of sediment.     

Description of the Inter-laboratory Comparison Programme in the New Zealand dairy industry

The Inter-laboratory Comparison Programme (ILCP) is a quality assurance system administered by the Dairy Division of the Ministry of Agriculture and Fisheries to monitor the performance of agency certified laboratories (ACLs). The programme works on a monthly basis during the milk producing season and is co-ordinated from the National Dairy Laboratory (NDL). Samples are despatched to Regional Dairy Labora-tories (RDL) and to the ACLs 2 weeks later. The RDL results are used to calculate an official mean. The ACL results are sent to the RDL where they are scrutinized immediately; hence, a rapid feedback on the ACL performance is possible. The NDL despatches a detailed statistical evaluation of results of ACLs and RDLs. The pro-gramme has increased from seven products in 1977 to eleven in 1984. Microbiological and chemical analyses are performed. A bacterial identification scheme to monitor E. coli and S. aureus was included in 1982. A scoring system (0 poor-10 good) which includes a weighting for specific tests and which is measured against an 'official' score has been introduced into a report which is distributed to all participants. The data generated by the programme are used by both ACLs and RDLs to check their analytical performance and quality control. Data are used by Dairy Division, as a national compilation of results issued by it which serves to highlight problem analyses, season trends and analytical limits.     

Frictional assessment of magnesium stearate and palmitate lubricant powders

A method has been developed for the frictional assessment of powder lubricants using a shear-box tester similar to that employed by Jenike. One commercial magnesium stearate, three high-purity magnesium stearates and three high-purity magnesium palmitates were assessed using this method. Powders with a well-ordered crystal structure and particle shape have a lower initial maximum coefficient of friction μ_a. The difference between μ_a and μ_b, the equilibrium dynamic friction coefficient, gives an indication of lubricant film-forming propensity. The basic friction equation is obeyed by the powders for most of the load range studied but deviates slightly approaching zero normal load.