Search

High voltage overhead reticulation lines are particularly vulnerable to lightning activity due to the lower basic insulation level (BIL) inherent to their design. Furthermore, in the South African context, these feeders often stretch over hundreds of kilometers and are often built on terrains that are difficult to access. These factors necessitate the use of some form of fault locating device. Some modern relays do have fault locating ability built into them. They do however not cater for lines of a heterogeneous nature. They also require inputs from voltage transformers, which make them expensive to operate under certain conditions. This project is aimed to develop a Microsoft-based software programme to locate intermittent faults on high-voltage radial overhead reticulation feeders.

Energy is a very important aspect of the present day daily life, and the need for monitoring and control is increasing over the years with sole purpose of saving energy and money. Chiller and Boiler plants at the Net-care private hospital still operate non monitored energy or control system. The advanced control and metering systems will be used to measure, monitor and in future used to control. This paper proposes a new model of monitoring of energy for cost saving.

The physiological, microbiological and chemical quality changes were studied in carrots that received preharvest sprays of a commercial plant extract (ComCat) and subjected to disinfection and storage at 1 and 22C. At harvest, ComCat-treated carrots had less aerobic and coliform bacteria population, higher contents of total available carbohydrates (TACs) and sucrose and lower glucose and fructose concentrations. During storage, ComCat-treated carrots displayed reduced physiological weight loss (PWL) with lower sucrose, glucose and fructose concentrations. Disinfectants reduced microbial populations in carrots. Chlorine disinfection resulted in an etched surface, which was not observed for anolyte treatment. Anolyte water showed a better positive effect on PWL. Higher temperatures deteriorated quality characteristics of carrots. The TAC accumulated better in ComCat-treated than in control carrots stored at room temperature. The combined effect of pre- and postharvest treatments had significant effect on maintaining postharvest quality and improvement of shelf life of carrots. PRACTICAL APPLICATIONS Preharvest ComCat treatment can be used to improve the overall quality of carrots. Disinfection of carrots using anolyte water was found to be superior to the chlorinated water dipping treatments. Thus, anolyte water is recommended for disinfection of carrots. Combining the preharvest ComCat treatment and disinfection using anolyte water, coupled with refrigerated storage environment should be used in the shelf life extension of carrots.

The potential to control leaf rust (Puccinia triticina; pathotype UVPt9) in vivo in susceptible (Thatcher) and resistant (Thatcher/Lr15) near-isogenic wheat (Triticum aestivum) lines by foliar applications of crude plant leaf extracts from Tulbaghia violacea and Agapanthus africanus, as well as a commercially available natural product, ComCat®, and a Lupinus albus seed suspension (SS) was investigated. In vitro activities of the PR-proteins, β-1,3-glucanase, chitinase and peroxidase were quantified in these two wheat lines under both non-infected and infected conditions. Although foliar application of the different plant extracts accelerated the activities of all three enzymes in resistant infected wheat plants, it was only the A. africanus extract that increased the in vitro activities of the three apoplastic pathogenesis-related proteins significantly in both susceptible and resistant wheat cultivars, whether uninfected or infected. The latter resulted in the reduction of pustule and necrotic lesion formation in the susceptible and resistant wheat lines, respectively. Foliar treatment of wheat seedlings with either ComCat® or SS had no effect on pustule and necrotic lesion formation. The A. africanus crude extract also had a significant in vitro inhibitory effect on both leaf rust spore germination and subsequent germ tube development.

Crude extracts of various Agapanthus africanus plant parts were screened in vitro against eight economically important plant pathogenic fungi. Radial mycelial growth was inhibited significantly ( P Pythium ultimum , and to a lesser extent Fusarium oxysporum and Alternaria alternata , showed a degree of tolerance. Subsequently, these crude extracts were tested in vivo in the greenhouse against Mycosphaerella pinodes , the cause of black spot or Ascochyta blight in peas. Fourth internode leaves were removed from 4-week-old pea plants, placed on moist filter paper in Petri dishes and inoculated with a M. pinodes spore suspension 30 min before and after treatment with the extracts. The control of Ascochyta blight by different concentrations of the crude extracts was measured in terms of lesion size over a 6-d period at 20 °C in a growth cabinet. All crude extracts significantly reduced lesion development caused by M. pinodes when leaves were inoculated with spores both before and after treatment with the extracts. Neither of the extracts showed any phytotoxic reaction on the leaves, even at the highest concentration applied. A combined aerial part crude extract of A. africanus was additionally evaluated against sorghum covered ( Sporisorium sorghi ) and loose ( Sporisorium cruentum ) kernel smuts under field conditions over two seasons. The extract and a standard fungicide, Thiram that served as a positive control, were applied as seed treatments 1 h after artificially inoculating separate sets of sorghum seed with smut spores. Inoculated, but untreated seeds served as a negative control. The extract reduced the incidence of both loose and covered kernel smuts significantly ( P A. africanus possesses sufficient in vivo antifungal activity to warrant a further investigation.

Carrots (Daucus carota L.) were dipped in anolyte water for 5, 10 and 20 min or in 100 μg/mL chlorine supplemented water for 20 min to study the effect of anolyte water as an environmentally friendly alternative disinfecting measure for carrots prior to packaging and storage. Packages of carrots were stored at 1 ± 0.5C and ambient temperature (17.5–31.4C). The anolyte water dipping treatment was found to be as effective as chlorinated solutions in controlling growth of aerobic bacteria, molds, yeasts and coliform bacteria during storage. There were no significant differences (P < 0.05) in microbiological changes on carrots dipped in anolyte water for 5, 10, and 20 min. Exposure of carrots to anolyte water for as short as 5 min can be used effectively to reduce and limit growth of aerobic bacteria, molds, yeasts and coliform bacteria. Losses in firmness and physiological weight were higher in carrots dipped in chlorinated water. Anolyte water treatments had no effect on total soluble solid content, pH value, firmness and the overall visual appearance of carrots.

Extracts from 26 plant species representing 16 families, collected in the Free State Province of South Africa, were tested in vitro for their potential to inhibit the growth of eight plant pathogenic fungi and five plant pathogenic bacteria. None of the crude extracts showed any mycelial growth inhibition of the eight test fungi. All of the extracts inhibited the growth of one or more of the five plant pathogenic test bacteria, but to varying degrees. Crude extracts from Acacia karroo and Elephantorrhiza elephantina inhibited the growth of four bacteria, while that of Euclea crispa, Acacia erioloba, Senna italica and Buddleja saligna inhibited the growth of all five plant pathogenic bacteria. Of these, the crude extract of Euclea crispa was clearly superior to the rest as it compared more favourably to that of a commercial bactericide, Dimethyl Dodecyl Ammonium Chloride (DDAC). Subsequently, the Euclea crispa crude extract was fractionated by means of liquid-liquid extraction using four organic solvents, hexane, diethyl ether, chloroform and ethyl acetate, in order of increasing polarity. This was done in an attempt to assess the antimicrobial potential of the more concentrated fractions. Once again, none of the semi-purified fractions showed any antifungal activity. However, antibacterial activity was located in the more polar ethyl acetate fraction indicating that the substances involved were very similar in polarity and/or structure. From this it seems justified to further purify the ethyl acetate fraction of the Euclea crispa extract and attempt to identify the active substance(s) involved.

Numerous indicators in South African society suggest the existence of attitudes of prejudice towards immigrants, especially non-Protestanis and those coming from countries other than White South Africa's traditional countries of origin. It would appear that the Afrikaans- and English-speaking communities differ in the social distance expressed towards immigrants. This paper deals with a survey in Pretoria to determine the social distance expressed towards Britishers, Germans, Greeks, Italians, the Dutch and the Portugese, by a number of adult White South African citizens. A modified Bogardus social distance test was used to determine the attitudes of 1.020 respondents who were found to be representative of the population in respect of sex, language, religious affiliation, marital status and age composition. Contrary to the hypothesis it was found that the Afrikaans-speaking sample was not Closer in social distance to the Dutch and Germans than were the English-speaking respondents. The hypothesis...

Conflicting results in the literature regarding the possible regulatory role of the embryonic axis on reserve mobilization in lipid-rich seeds prompted this study on cucumber ( Cucumis sativus ) seed. Two existing models supporting control by the axis, namely the hormonal control- and source-sink relationship models, were tested by incubating detached cotyledons in plant hormone solutions and axes extracts as well as in the presence of artificial sinks. This approach was an attempt to alleviate any effect that axis removal might have on reserve mobilization in cotyledons measured in terms of changes in fresh and dry weight, respiratory capacity and isocitrate lyase activity. No clear evidence that lipid mobilization in cucumber seeds was controlled by the axis through either a hormonal- or a source-sink mechanism was obtained. However, axis removal prevented the natural shedding of the testa by germinating cucumber seeds resulting in clear differences between intact and detached cotyledons in terms of fresh and dry weight, respiratory and lipid metabolism. Moreover, weakening of the testa on detached cotyledons, by cutting longitudinally, only partially alleviated the inhibitory effect that axis removal had on these metabolic events while total removal alleviated this effect completely. The latter was more pronounced in an elevated oxygen atmosphere indicating that the testa played a more pronounced role in controlling the metabolism of cucumber cotyledons during the post-germinative seedling establishment phase than did the growing axis.

Leaf samples of Euclea crispa subsp. crispa were collected in the Bloemfontein area of the Free State Province as part of a project to screen South African plants for their antimicrobial potential. Crude extracts were obtained with a 95% methanol solution and the aqueous fraction remaining after methanol was removed by distillation, was bioassayed in vitro for its potential to inhibit the growth of eleven human pathogenic bacteria and two human pathogenic fungi. Of all the plant extracts tested, the E. crispa crude leaf extract showed the most promising antimicrobial activity against human pathogenic bacteria and fungi. Subsequently, the crude extract was fractionated by means of liquid-liquid extraction using four different organic solvents in order of increasing polarity. Most of the antibacterial activity was observed in the more polar ethyl acetate fraction. No particular trend of inhibition was observed between the Gram-negative and Grampositive bacteria. Neither the crude extract nor the semipurified fractions inhibited the growth of Haemophilus influenzae, Klebsiella pneumoniae and Streptococcus pneumoniae. The growth of the other eight human pathogenic bacteria was inhibited to different degrees. Both the crude extract as well as all the semi-purified fractions inhibited the growth of two human pathogenic test fungi.