In Australia the protection of building timbers from termites relied for many years upon the application of persistent organochlorines as well as the organophosphate compound (chlorpyrifos) and the synthetic pyrethroid (bifenthrin) as soil chemical barriers (Lenz et al. 1990; Watson, 1990; NHMRC, 1992; AS 3660.1 1995). The persistent organochlorines have been banned since 1987 in the USA and from June 1995 in all Australian states except the Northern Territory. The study evaluated the life-cycle of boron as an alternative wood preservative, its toxicity to foraging populations of subterranean termites (‘termites’) over time were particularly referred to the influence of foraging space and determined a suitable loading of boron in timber for hazard class2 (H2) conditions as defined in Australian standard-1997. Preservative treatment of timber according to Australian Standard 1604 (1997) prevents attack and damage of wood and wood products from biodeteriogens (namely fungi and insects). Above-ground interior timber framings are not normally liable to decay but to damage by wood-destroying insects. The study examined the use of borates as wood preservatives to prevent attack and damage by subterranean termites (‘termites’) of the genus of Coptotermes. In addressing the aims of this study, several different avenues of approach were followed. The chapter sequence in this thesis follows the pattern of measuring the effects of borates on a wide range from 20 termites in laboratory bioassay to thousands of termites in natural colonies.

This paper discusses the development of a microprocessor-based instrument to measure boron concentration in the cooling water of a pressurized water reactor. The technique used to develop the boronimeter is neutron transmission entailing the use of a neutron source and a bank of detectors to measure the absorbed neutrons in a sample of borated water. A unique feature of the boronimeter is the inclusion of a servo-operated absorber sleeve which is automatically positioned to compensate for changes in boron concentration. The sleeve is positioned to keep the count rate constant and the position of the sleeve is then used to determine the concentration of the sample. The null operation feature makes the boronimeter particularly adaptable to on-line operations owing to the improved counting statistics. Tests completed on the boronimeter demonstrate its usefulness for accurate, rapid analysis of boron concentration. The system was calibrated over the concentration range 0-2500 ppm boron. At a concentration of 1000 ppm the standard deviation was ± 2% for an analysis time of < 4 minutes. / Master of Science

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published_or_final_version / Mechanical Engineering / Doctoral / Doctor of Philosophy

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There is a constant need for robust and highly reactive hydroborating reagents which will be able to yield stable organoborane compounds upon their hydroboration with olefins. These stable organoborane compounds can be used as a starting material in a number of cross-coupling reactions. The objectives of this project were to synthesize heterocyclic borolanes (with mixed donor atoms) and to evaluate the stability and reactivity of such borolanes towards the hydroboration reaction. The second part of the objective was to evaluate the application of arylbenzo-1,3,2-diazaborolane compounds as potential arylating reagent in the copper(II)acetate catalyzed N-arylation of imidazole using the Chan-Lam coupling reaction. Three heterocyclic borolanes were successfully synthesized from the reaction of borane-dimethyl sulfide complex with the corresponding chelating group in yield ranging from 45-96 %. These borolane showed good stability towards atmospheric oxidation and disproportionation due to elevated temperatures. A density functional calculation conducted on these borolanes showed that there was an decrease in the gap energy in the order of benzo-1,3,2-dioxaborolane > benzo-1,3,2-oxothiaborolane > benzo-1,3,2-thiazaborolane > benzo-1,3,2-dithiaborolane > benzo-1,3,2-diazaborolane. The use of benzo-1,3,2-thiazaborolane as a hydroborating reagent showed that this compound was prone to disproportionation. The condensation reaction of boronic acid with 1,2-diaminophenyl, 1,2-dihydroxybenzene and o-aminophenyl mercaptan, resulted in the synthesis of eleven arylbenzo-1,3,2-boronate esters in yields between 66-99 %. The investigation on the use of arylbenzo-1,3,2-diazaboronate ester as N-arylating reagents in the Chan-Lam coupling showed that these compounds were unsuitable arylating reagents and that the boronic acid proved to be better arylating reagent. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2013.