Thesis (Ph.D.)--Murdoch University, 2003. / Thesis submitted to the Division of Arts. Bibliography: p. 273-289.

Thesis submitted to the Division of Arts. Bibliography: p. 273-289.

M.Tech. / Essential oils are volatile oils, generally odorous, which occur in certain plants or specified parts of plants, and are recovered by accepted procedures, such that the nature and composition of the product is, as nearly as practicable, unchanged by such procedures (ISO, 1968). The principal uses are as: flavouring agent, medicinal and aromatherapy application. Today, the essential oils are sought-after for innumerable applications starting from markers for plant identifications to bases for semi-synthesis of highly complex molecules. The extraction of highly delicate essential oils from plants remains a crucial step in all these applications. By using steam to mediate the extraction, it is possible to maintain mild conditions and effect superior extraction. In the current work, an integrated procedure for steam extraction followed by volatiles sampling and analysis from the leaves of the Eucalyptus tree was explored. There are two problems to overcome in the extraction from solid plant materials: that of releasing the essential oils from solid matrix and letting it diffuse out successfully in a manner that can be scaled-up to industrial volumes. Towards this end, the effect of different parameters, such as temperature, pressure and extraction time on the extraction yield was investigated and the experimental results show that all of these temperatures (90 °C, 97°C, and 99°C), were significant parameters affecting yield. Increase in yield was observed as pressure was increased and the use of high pressure (150 kPa) in steam extraction units permits much more rapid and complete distillation of essential oils over atmospheric pressure. The yield was calculated from the relation between the essential oil mass extracted and the raw material mass used in the extraction. The volatiles, Eucalyptus oil in vapour form released from the leaves were condensed and analyzed using Gas chromatography, and eight major components were found to be contained in this species. A mathematical model based on diffusion of essential oil from the leaves was developed. Using a numerical method, the best diffusion coefficient was established for different operating conditions by comparing the model concentration of oil remaining in the leaves with the experimental amount of oil recovered; hence minimizing the sum of squared errors. It was found that one cannot simply assume that the oil leached and recovered was the same as that originally present in the leaves. The initial mass of oil was determined by fitting the diffusion model to the data. An Arrhenius model was used to account for the effect of temperature. The resulting expression for the diffusion coefficient as a function of temperature can now be used to model the large scale extraction of the essential oils from Eucalyptus leaves.

Objetivo: Evaluar la eficacia disolvente de una sustancia experimental a base de Aceite esencial de Myrciaria dubia en la desobturación de conductos radiculares. Materiales y métodos: Se utilizaron 60 tubos de PLA (ácido poliláctico)que fueron divididos en 5 grupos de 12 especímenes. Estos se rellenaron con un material de restauración temporal (coltosol) el primer tercio y el tercio medio con gutapercha. Se añadió un total de 0,1 ml de disolvente dependiendo del grupo de estudio (Agua destilada,camu camu, xilol,aceite de cascara de naranja y de eucalipto) a la parte superior de los tubos de PLA. Después de 5 minutos, se utilizó la máquina Instron 5566 (Instron, Buckinghamshire, UK) se movió hacia abajo a través de gutapercha con una velocidad de cabecera de 5 mm / min a una profundidad de 5 mm min. La carga(fuerza) utilizada para penetrar el separador en la profundidad de 5 mm se registró en Newton. Para el análisis se realizará la prueba de kruskal Wallis para comparar la medida fuerza de penetración según el tipo de solvente, posterior a comprobarse los supuestos estadísticos. Resultados: Se encontraron diferencias estadísticamente significativas al comparar todos los solventes (p= 0.001), obteniendo 14.02N para la sustancia experimental. Los resultados de la profundidad de disolución superficial y la fuerza utilizada para penetrar el esparcidor a 5 mm revelaron que el Aceite de Myrciaria Dubia ( Camu Camu) fue significativamente el mejor solvente para ablandar la gutapercha (P <0.05), seguido del xilol y el aceite de cascara de naranja, mientras que el disolvente con menos efectividad fue el aceite de eucalipto. Conclusiones: El aceite esencial de Myrciaria Dubia presento mayor poder reblandecedor que las demás soluciones en estudio. / Objective: To evaluate the solvent efficacy of an experimental substance based on Myrciaria dubia essential oil in the desobturation of root canals. Materials and methods: 60 PLA (polylactic acid) tubes were used, which were divided into 5 groups of 12 specimens. These were filled with a temporary restoration material (coltosol) the first third and the middle third with gutta-percha. A total of 0.1 ml of solvent was added depending on the study group (distilled water, camu camu, xylol, oil of orange peel and eucalyptus) to the top of the PLA tubes. After 5 minutes, the Instron 5566 machine (Instron, Buckinghamshire, UK) was used and moved down through gutta-percha with a head speed of 5 mm / min at a depth of 5 mm min. The load (force) used to penetrate the separator to the depth of 5 mm was recorded in Newton. For the analysis, the kruskal Wallis test will be carried out to compare the penetration force measure according to the type of solvent, after checking the statistical assumptions. Results: Statistically significant differences were found when comparing all solvents (p = 0.001), obtaining 14.02N for the experimental substance. The results of the surface dissolution depth and the force used to penetrate the spreader to 5 mm revealed that Myrciaria Dubia Oil (Camu Camu) was significantly the best solvent to soften gutta-percha (P <0.05), followed by xylol and orange peel oil, while the least effective solvent was eucalyptus oil. Conclusions: The essential oil of Myrciaria Dubia presented greater softening power than the other solutions under study. / Tesis

M. Tech. (Department of Chemistry, Faculty of Applied and Computer Sciences), Vaal University of Technology. / The world is continuously losing the battle against superbugs (resistant bacteria towards commonly used antibiotics), hence there is an urgent need to develop novel antibacterial agents. In this study, green synthesized silver nanoparticles (AgNPs) and eucalyptus oil, were incorporated into the polymer blend fibres of polyvinyl alcohol (PVA) and cellulose nanocrystals (CNC’s). Various techniques were used to characterize the AgNPs, PVA/CNC polymer fibres, and PVA/CNC incorporated with AgNPs/eucalyptus oil. The morphology of AgNPs synthesized using an increasing concentration of the Citrus sinensis peels (CSP) extract was obtained from transmission electron microscopy (TEM). AgNPs synthesized using 1 and 2 % m/v (CSP) were agglomerated and whereas those synthesized using 3 % m/v of the extract were spherical with an average particle size 10 ± 1.2 nm. UV/Visible absorption spectra for all the synthesized AgNPs exhibited a surface plasmon resonance (SPR) peak at around 400 nm which is a characteristic peak of silver. Significant shifts in the absorption peaks or maxima were observed to signify changes in the shape and size of the nanoparticles. Scanning electron microscopy (SEM) was used to study the morphology of the fabricated polymer fibres. The Addition of CNC’s to PVA resulted in an increase in fibre diameter due to an increase in viscosity of the solution. An increase in the concentration of silver nanoparticles and the eucalyptus oil in the PVA/CNC resulted in a decrease in fibre diameter due to an increase in conductivity of the material. The fibres with AgNPs were smooth while the ones with the eucalyptus oil were beaded. X-ray diffraction (XRD) showed the presence of the AgNPs in the polymer fibres and Fourier transform infrared (FTIR) showed the presence of the functional groups that are available in the eucalyptus oil. The antibacterial efficiency of the PVA/CNC incorporated with AgNPs, eucalyptus oil, and the mixture of AgNPs and the eucalyptus oil was investigated using S. aureus and K. pneumoniae. All the materials showed significant inhibition of the growth of the selected bacterial strains. PVA/CNC polymer fibres incorporated with AgNPs showed higher antibacterial activity compared to PVA/CNC polymer fibres incorporated with eucalyptus oil.

[Truncated abstract] Insufficient water use by annual crop and pasture species leading to costly rises in saline watertables has prompted research into potentially profitable deep-rooted perennial species in the Western Australian wheatbelt. Native mallee eucalypts are currently being developed as a short-rotation coppice crop for production of leaf oils, activated carbon and bio-electricity for low rainfall areas (300—450 mm) too dry for many of the traditional timber and forage species. The research in this study was aimed at developing a knowledge base necessary to grow and manage coppiced mallee eucalypts for both high productivity and salinity control. This firstly necessitated identification of suitable species, climatic and site requirements favourable to rapid growth, and understanding of factors likely to affect yield of the desirable leaf oil constituent, 1,8-cineole. This was undertaken using nine mallee taxa at twelve sites with two harvest regimes. E. kochii subsp. plenissima emerged as showing promise in the central and northern wheatbelt, particularly at a deep acid sand site (Gn 2.61; Northcote, 1979), so further studies focussed on physiology of its resprouting, water use and water-use efficiency at a similar site near Kalannie. Young E. kochii trees were well equipped with large numbers of meristematic foci and adequate root starch reserves to endure repeated shoot removal. The cutting season and interval between cuts were then demonstrated to have a strong influence on productivity, since first-year coppice growth was slow and root systems appeared to cease in secondary growth during the first 1.5—2.5 years after cutting. After decapitation, trees altered their physiology to promote rapid replacement of shoots. Compared to uncut trees, leaves of coppices were formed with a low carbon content per unit area, and showed high stomatal conductance accompanied by high leaf photosynthetic rates. Whole-plant water use efficiency of coppiced trees was unusually high due to their fast relative growth rates associated with preferential investments of photosynthates into regenerating canopies rather than roots. Despite relatively small leaf areas on coppice shoots over the two years following decapitation, high leaf transpiration rates resulted in coppices using water at rates far in excess of that falling as rain on the tree belt area. Water budgets showed that 20 % of the study paddock would have been needed as 0—2 year coppices in 5 m wide twin-row belts in order to maintain hydrological balance over the study period. Maximum water use occurred where uncut trees were accessing a fresh perched aquifer, but where this was not present water budgets still showed transpiration of uncut trees occurring at rates equivalent to 3—4 times rainfall incident on the tree belt canopy. In this scenario, only 10 % of the paddock surface would have been required under 5 m wide tree belts to restore hydrological balance, but competition losses in adjacent pasture would have been greater