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Labeling of consumer products is not only required by regulatory bodies for product identification, but it also serves as a symbol of product quality and prestige. Bubbles under the label are unsightly and impact customer satisfaction. Pressure Sensitive Adhesive (PSA) labels currently make up more than eighty percent of all labels in the market today, yet little research could be found addressing causes of bubbling in an industrial setting. A root cause analysis for bubble development included four aspects: label application, environmental conditions of shipping and storage, defects in glass bottle geometry, and oil contamination. The most significant findings from each area were as follows: Label Application. Force and contact time were confirmed to be significant factors in reducing label bubbling. The equipment settings directly related to these factors should be controlled and monitored. Environmental Conditions. None of the environmental conditions caused growth or appearance of additional bubbles as was the hypothesis. All 4 test conditions had a significant Paired T-test but in the reduction of bubble size. Glass Defects. A random sample of bottles showed very poor capability of the bottle dimensions. However, low capability to produce within specification limits does not necessarily lead to bubbling. A direct comparison test was done to compare diameters and variation from bubbled bottles to non-bubbled. No measurements that could reasonably be related to bubbles caused by glass defectiveness were statistically different. Oil Contamination. Initial data analysis showed that certain oil types had a higher chance of causing bubbling. However, after a controlled experiment was performed, the results were inconclusive that oil contamination pre or post-labeling could cause bubbling in isolation. The experiment did confirm the importance of sufficient pressure in the label application process.

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M.S.

The effect of kinetin concentrations (10⁻⁶M and 10⁻⁴M) on distribution of free fatty acids and sterols in plant parts and root exudates of 57-day-old peanut plants grown in nutrient solutions under gnotobiotic conditions was studied. Kinetin was applied to the roots in the culture medium five days before harvest. Upon harvesting root exudates were collected and plants divided into leaves, stems, and roots. The extracted lipid fraction was partitioned using silica gel thin-layer chromatography. Quantitation and identification of free fatty acids and sterols were accomplished by isothermal gas-liquid chromatography. On the basis of ug fatty acid/mg tissue and ug fatty acid/mg lipid kinetin caused no significant changes in total fatty acid concentration. The only significant increase in total sterol concentration was observed in the 10⁻⁴M treatment (ug sterol/mg lipid) in the stems. Use of individual component concentrations, relative percentages, and ratios helped distinguish trends. Shifts in quantity and quality of the free fatty acids and sterols may have been a result of one or a combination of effects attributed to kinetin. Decrease in root exudation in the 10⁻⁶M treatment may have been due to altered membrane integrity. Increase in the sitosterol/ stigmasterol ratio in stems of treated plants may have been a result of delayed senescence. Trends showed transport of free fatty acids and sterols to the roots in 10⁻⁶M treated plants. Kinetin may have effected sterol concentration through changes in HMGCoA reductase activity by unsaturated fatty acids. / Master of Science

The object of this thesis was to investigate some of the factors that night effect the oil film performance between piston rings and cylinder walls. An apparatus was constructed to measure the instantaneous changes in resistance across the oil film. A piston ring of an air-cooled single cylinder engine was insulated from the rest of the piston using Teflon. A bridge circuit was used to feed the unbalanced signals to an oscilloscope. The traces on the oscilloscope were recorded by means of an Polaroid-Land recording camera. An external motor having a speed control system was used to drive the engine. It was found from this investigation that the lubrication could be improved by increasing the engine speed and oil viscosity. More metallic contact was found when the engine was under its own power. The results also showed that the breakdown of oil film occurred when the oil temperature was increased. The experimental results indicated that the piston ring and the cylinder wall were never separated by lubricating oil at dead centers. The breakdown of oil film occurred at these positions in every case. / Master of Science

A dissertation submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the Degree of Master of Science. Johannesburg, 2014. / Aromatic plants and oils have been used for thousands of years in perfumes, and cosmetics and for their culinary and medicinal purposes. The essential oil from Centella Asiatica growing specifically in South Africa has many therapeutic uses and is used to treat various diseases. Different extraction methods were used on the leaves of Centella Asiatica and the composition of each sample of oil obtained was analysed to see how the composition of each sample is affected. The methods of extracting were optimised specifically for Centella Asiatica. The different extraction methods used were steam distillation, water distillation, solvent extraction and soxhlet extraction. Steam and water distillation were preformed with three different apparatus to compare the efficiency of the extraction and the affect on composition of the oil. It was found that steam distillation using the apparatus described by the British Pharmacopedia Volume IV was the most sufficient apparatus to use to obtain the greatest yield of oil. Soxhlet extraction was found to be the worst extraction method for volatile compounds The optimised parameters for extraction of essential oils from Centella Asiatica using this apparatus were 100 g of leaves at a distillation rate of 2/3 ml min-1 for 75 minutes using 0.4 ml of xylene initially. It was also necessary to perform a 30 minute initial distillation with no plant matter. Steam distillation with this apparatus was found to yield the best quality oil. The major constituents that were found in all the methods were α-carophyllene, carophyllene and germacrene D. There were some similarities found in the compositions of the essential oil between extraction methods in terms of the constituents found. However the abundance of those constituents varied between extractions. Each constituent has a different therapeutic effect. Therefore if an extraction method were to be chosen to extract a some specific constituent like germacrene D and α-carophyllene, steam distillation with the apparatus described by the British Pharmacopedia should be used. However if an extraction method were to be used to extract carophyllene, water distillation should be used. The essential oil extracted using steam distillation yielded a greater amount sesquiterpenoid hydrocarbons. However monoterpenoid hydrocarbons were present in greater amount in the essential oil extracted using water distillation. In the essential oil extracted from Centella Asiatica, 43 constituents were identified from steam distillation extraction representing 98.60% of the composition of oil and 54 constituents representing 98.29% from water distillation extraction. It was found that from steam distillation using fresh leaves compared to dry leaves extraction a greater number of constituents were identified. Salting out was also used for extraction and compared to water distillation and it was found that the salting-out extractions yielded a greater amount of oxygenated polar compounds. A commercial oil of Centella was also analysed and compared to the natural oil. It was found that the commercial oil was a synthetic oil and its composition was completely different from the natural oil and therefore synthetic oils cannot be used therapeutically for substitutes for natural essential oils. Centella Asiatica prefers to grow in damp environments, therefore they are extremely prone to pollution. This was found to also affect the chemical composition of the oil obtained since the soil quality of where the plants were growing was important. This was investigated by spiking the soil of some Centella asiatica plants with chromium(VI), mercury(II) and lead(II). It was found that Centella Asiatica can store heavy metals in the leaves. Since it is a medical plant with many therapeutic uses, this is causes great concern about heavy metal contamination of herbal raw materials of Centella Asiatica. This also highlights the importance of good quality control on Centella Asiatica, so that heavy metals are not ingested. The people in the rural areas who use it as a raw plant for herbal preparations could be at risk of ingesting heavy metals if grown in a polluted area.