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Please read the abstract in the section 00front of this document / Dissertation (MSc (Applied Chemistry))--University of Pretoria, 2006. / Chemistry / unrestricted

Two labdane diterpenoids 8-hydroxymarrubiin and leonitin were isolated from Leonotis dysophylla (Benth.) and Leonotis leonitis respectively. Spectral studies of 8-hydroxymarrubiin, C₂₀H₂₈ O₅ʻ showed the presence of a β -substituted furan, a Ϫ-lactone, three tertiary methyl groups and tertiary hydroxyl group (s). The NMR spectrum of 8-hydroxymarrubiin and marrubiin C₂₀H₂₈O₄ʻ were almost identical with the exception of the C₁₇- methyl group which appeared as a singlet in 8-hydroxymarrubiin and as a doublet in marrubiin. The extra oxygen atom was therefore assumed to be present as a hydroxyl group substituted in the C₈₋ position. This was further confirmed by the formation of an epoxide and a Ϫό-dilactone. Leonitin, C₂₀H₂₈O₇ʻ was shown by spectral and chemical evidence to be a diterpenoid dilactone possessing an ester function and an ether linkage. Comparison of the NMR spectra of compound X and leonitin suggested that the acetoxy function occurs in the C₂₀- position. This was further supported by the formation of a 'Ϫό -dilactone. The absence of a β -furan moiety was apparent from chemical and spectral evidence, A structure for leonitin is proposed and aspects of its stereochemistry discussed.

Recent experiments [P. Brunet, J. Eggers, and R. Deegan, Phys. Rev. Lett. 99, 114501 (2007)] have shown that a liquid droplet on an inclined plane can be made to move uphill by sufficiently strong, vertical oscillations. In order to investigate this counterintuitive phenomenon we will derive three different models that qualitatively reproduce the main features of the experiment. For the first model the liquid's inertia and viscosity are assumed negligible, so that the motion of the droplet is dominated by the applied acceleration due to the oscillation of the plate, gravity and surface tension and that the droplet is thin. We explain how the leading order motion of the droplet can be separated into a spreading mode and a swaying mode. For a linear contact line law, the maximum rise velocity occurs when the frequencies of oscillation of the two modes are in phase. We show that, both with and without contact angle hysteresis, the droplet can climb uphill and also that, for certain contact line laws, the motion of the droplet can produce footprints similar to experimental results. We show that if the two modes are out of phase when there is no contact angle hysteresis, the inclusion of hysteresis can force them into phase. This in turn increases the rise velocity of the droplet and can, in some cases, cause a sliding droplet to climb. For the second model we use a two-dimensional flow where the Reynolds number is assumed large enough for viscosity to be neglected. We show that the leading order motion of the droplet can be separated into the same two modes and the net motion of the droplet is an oscillatory function of the frequency. For increasingly non-wetting droplets we discover that the rise velocity begins to oscillate very rapidly as a function of the static contact angle. What we also discover is that the change in the free surface of the droplet is actually a wave travelling travelling across the droplet, and the amount of modes present coincide with the rapid change in the rise velocity. Using a cubic contact line law and contact angle hysteresis we observe a droplet that can climb uphill for parameter values similar to that of the experiment. With the addition of a time dependent term within the contact line law we show that it is possible to obtain a multi-valued relationship between the velocity of the contact line and the respective contact angles, reproducing experimental observations seen for unsteady, moving contact lines. For the third model we again assume that the liquid's viscosity is negligible, similar to model 2, only now for a three-dimensional, thin droplet. For very small amplitudes the motion of the droplet is a combination of a swaying mode and a spreading mode that interact causing a net motion of the droplet. This motion is found to be an oscillatory function of the driving frequency and the magnitude of the peak rise velocity is proportional to one over the frequency squared. By examining the velocity of the centre of the droplet and the displacement of the contact line we see that the absolute maximums of both of these, over one period of oscillation, contain natural frequencies, which are evenly spaced with respect to the square root of the frequency of the oscillation.

Cette thèse de doctorat est consacrée à la pensée du philosophe américain Nelson Goodman (1906-1998). Nous y défendons, à l’encontre de la plus grande partie de la critique, une lecture métaphysicienne de son œuvre. Il est démontré que Goodman, dans tous ses travaux, développe une métaphysique technique et méconnue, dont les piliers sont le nominalisme, le pluralisme, le perdurantisme, l’actualisme, et l’universalisme méréologique. Cette lecture permet de réévaluer l’ensemble de la pensée goodmanienne. Elle établit aussi ses liens insoupçonnés avec la métaphysique analytique contemporaine.

The availability of water can be considered as one of the key ingredients to the human life, yet this resource remains scarcely available to those living in the rural parts of Africa. When water does present itself, it is often impure and requires extensive treatment. Water treatment systems, particularly those capable of treating water in rural areas, are currently areas of research and entrepreneurship focus, making a number of potential solutions available, and other still coming in. Unfortunately, these systems are not always capable of performing in particular socio-cultural and economic contexts, or are often deployed in the wrong rural areas. Therefore these systems do not perform at their optimal level of design. Rural areas in Africa have different socio-cultural and economic context from each other, and this needs to be taken into account if one is going to select the right water treatment system for a particular area. Using industrial engineering tools, two water treatment system selection models; an Additive Analytic Hierarchy Process model and a Fuzzy Logic based model, are presented and then integrated. These models take into account the context of selected rural area by pitting available water purification systems against selected criteria to determine if it is the right fit for the rural area considered. Both models are then pitted against each other to determine which is more adept at selecting the appropriate water purification system. Three water treatment alternatives were considered after an analysis was conducted on the available solutions on the market. The water treatment systems under consideration were the Biosand Filter with Zeolites (BSFZ), the Silver Impregnated Porous Pot, and A Borehole system. Makwane, a rural village in Limpopo, South Africa was used as a case study to demonstrate the application of the selection models. The BSFZ was selected as the ideal water treatment system to be implemented in Makwane / Dissertation (MEng)--University of Pretoria, 2016. / Industrial and Systems Engineering / MEng / Unrestricted

The present chemical and physical methods for the determination of ethyl alcohol are all subject to systematic errors derived from any of a number of interfacing substances usually present in solution with the ethanol. Some of the most popular methods are slow and tedious and require a good deal of skill and technique to perform. The dichromate (2), pycnometer and refractometer methods are three such methods. The interfering substances most often present in industrial and food products are fusel oils and acetaldehyde. These substances interfere in the three methods just mentioned. It is of course possible to analyze for these substances separately and then make appropriate corrections, or to remove them before the determination is performed; but by either method the total analysis time is quite lengthy and tedious. In many cases throughout industry the determination of ethyl alcohol is a routine analysis which is usually performed by lab technicians with limited chemical background and thus lengthy and difficult methods of analysis should be minimized. The ideal method would be one which is rapid, accurate, specific and one which can be performed easily by a skilled technician. Gas chromatography is an analytiucal tool which has not yet been thoroughly investigated as a means of determining ethanol in aqueous solutions and is one which can virtually eliminate many of the undesirable features of the present chemical and physical methods. It is the purpose of this thesis to add to this investigation by presenting a moderately rapid gas chromatographic method and a high speed gas chromatographic method for this analysis and to compare these to the pycnometer and micro-dichromate methods presently used. The purpose of presenting two methods is to provide the user some choice depending on his needs and facilities.

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In this thesis, classical computation is first introduced. Finite quantum systems are considered with D-dimensional Hilbert space, and position x and momentum p taking values in Z(D) (the integers modulo D). An analytic rep resentation of finite quantum systems that use Theta function is presented and considered. The first novel part of this thesis is contribution to study reversible classical CNOT gates and their binary inputs and outputs with reversible cir cuits. Furthermore, a reversible classical Toffoli gates are considered, as well as implementation of a Boolean expression with classical CNOT and Toffoli gates. Reversible circuits with classical CNOT and Toffoli gates are also considered. The second novel part of this thesis the study of quantum computation in terms of CNOT and Toffoli gates. Analytic representations and their zeros are considered, while zeros of the inputs and outputs for quantum CNOT and Toffoli gates are studied. Also, approximate computation of their zeros on the output are calculated. Finally, some quantum circuits are discussed. i

Quantum systems with a finite Hilbert space, where position x and momen- tum p take values in Z(d) (integers modulo d), are studied. An analytic representation of finite quantum systems is considered. Quantum states are represented by analytic functions on a torus. This function has exactly d zeros, which define uniquely the quantum state. The analytic function of a state can be constructed using its zeros. As the system evolves in time, the d zeros follow d paths on the torus. Examples of the paths ³n(t) of the zeros, for various Hamiltonians, are given. In addition, for given paths ³n(t) of the d zeros, the Hamiltonian is calculated. Furthermore, periodic finite quantum systems are considered. Special cases where M of the zeros follow the same path are also studied, and general ideas are demonstrated with several ex- amples. Examples of the path with multiplicity M = 1; 2; 3; 4; 5 are given. It is evidenced within the study that a small perturbation of the initial values of the zeros splits a path with multiplicity M into M different paths. / Libyan Cultural Affairs