Today, manual polishing is the most common method to improve the surface finish of mould and dies for e.g. plastic injection moulding, although it is a cumbersome and time-consuming process. Therefore, automated robots are being developed in order to speed up and secure the final result of this important final process. The purpose of this thesis is to find out some clues about the influence of different parameters for the polishing of a steel grade called Mirrax ESR (Uddeholm Tooling AB) using a Design of Experiment. The report starts with a brief description of mechanical polishing (the techniques and polishing mechanisms) and ends up with the optimization of the polishing procedure with a polishing machine, the Strecon RAP-200 made by Strecon A/S. Even if all the runs of the Design of Experiments couldn’t be carried out, the surfaces studied revealed some information about the importance of the previous process (turning marks not removed) and about the link between the aspect of the surfaces and the roughness parameters.

Dracula is a novel that has been said to have flat and uninteresting characters. Only two characters have been acknowledged as having depth, Wilhelmina Harker and Abraham Van Helsing. However, no extensive research has been done to determine what it is that makes them complex, leaving a gap in the understanding of Dracula. This essay will appraise the significance of the two characters to the novel by examining how they are characterised and by studying their importance to the plot. This allows for a new perspective on Dracula that revises the standard generic definition of the novel as Gothic. The stereotypical characters in Gothic novels are replaced with more intricate characters and subtleties. For instance, this essay argues that one can find Mina an ambiguous character who is stuck following rules she despises, and Van Helsing might be hiding his fear of Mina behind the mask of appreciation. Furthermore, the importance of Mina and Van Helsing to the plot, shown in several ways where the most prominent one is their associations with knowledge, changes what characters are the real protagonists of Dracula and shows another difference to the traditional Gothic novel. This essay reveals that there are holes in the Dracula research, and that many new readings can still be found. If one resists looking at the novel as purely Gothic, there are nuances that show that it does not quite fit the genre, and characterisation is one aspect that clearly differs.

Musical characterisation plays an important role in Britten's operas. The aim of this study was to determine how Britten depicts the diverse, dualistic characters in Billy Budd through music. Ambiguity, which is characteristic of this opera, is the result of the manner in which the plot is portrayed musically through developing motives. The conflict between the diverse characters in Billy Budd is depicted by the thematic material. The musical ideas and motives change as the plot becomes more complex. The method of investigation was, in the first instance, to analyse the musical ideas associated with each character. Second, the manner in which these ideas change through the course of the opera was pointed out. The story does not only concern itself with the relationship between good and evil. The fate of the three main characters, Billy, Vere and Claggart, is precisely the opposite of their true nature. Who they really are, is not reflected in their doings, as depicted by the integrated themes. Billy, the innocent boy, kills. Vere, the father figure, doesn't protect Billy on the day of his conviction. Claggart, who manipulates to have his own way, can't avoid his own death. This study shows that Billy is represented by the stammer figure and Vere by the "Starry Vere" motive. Vere's inner conflict is depicted by the ambiguous combination of a major third and minor third interval. The confusion that eventually leads to Billy's demise is represented by intervals of a perfect fourth, associated with Claggart. During the course of the opera, Vere's music is infiltrated by Claggart's motives. Billy is represented in the opera by the woodwind instruments, Vere by the strings and Claggart by the brass instruments. / Thesis (M.Mus.)--North-West University, Potchefstroom Campus, 2006.

This thesis presents the preparation of vertically aligned carbon nanotubes using porous anodic alumina templates via thermal chemical vapour deposition. The characteristics of prepared carbon nanotubes in terms of tube diameter, length, density, uniformity and alignment were investigated. The formation of porous anodic alumina membranes was studied. In order to prepare well-ordered porous anodic alumina templates, three approaches towards anodization of aluminium were examined. Effects of Al surface morphology and anodization conditions on the formation of the porous anodic alumina membrane were investigated. Co catalyst was electrochemically deposited at the bottom of the pores of porous anodic alumina templates by applying an alternating current. Prior to the AC electrodeposition, the barrier layer at the base of the pores was thinned in order to facilitate the deposition process. The thinning effect of three barrier layer thinning approaches was examined. The effect of electrodeposition duration on the pore filling was investigated. Carbon nanotubes were grown using Co-loaded porous anodic alumina templates via thermal chemical vapour deposition of C₂H₄. Effects of the presence of the Co catalyst, the amount of Co deposited at the bottom of the pores and the presence of water vapour on the carbon nanotube growth were examined. The characteristics of the grown carbon nanotubes in terms of tube diameter, length, density, uniformity and alignment were investigated. Moreover, a post-treatment after the carbon nanotube growth was proposed in order to obtain vertically aligned carbon nanotubes. In addition, vertically aligned carbon nanotubes were grown on Si chips. Two methods were used to prepare a catalytic layer on the Si chips for carbon nanotube growth.

No description available.

Musical characterisation plays an important role in Britten's operas. The aim of this study was to determine how Britten depicts the diverse, dualistic characters in Billy Budd through music. Ambiguity, which is characteristic of this opera, is the result of the manner in which the plot is portrayed musically through developing motives. The conflict between the diverse characters in Billy Budd is depicted by the thematic material. The musical ideas and motives change as the plot becomes more complex. The method of investigation was, in the first instance, to analyse the musical ideas associated with each character. Second, the manner in which these ideas change through the course of the opera was pointed out. The story does not only concern itself with the relationship between good and evil. The fate of the three main characters, Billy, Vere and Claggart, is precisely the opposite of their true nature. Who they really are, is not reflected in their doings, as depicted by the integrated themes. Billy, the innocent boy, kills. Vere, the father figure, doesn't protect Billy on the day of his conviction. Claggart, who manipulates to have his own way, can't avoid his own death. This study shows that Billy is represented by the stammer figure and Vere by the "Starry Vere" motive. Vere's inner conflict is depicted by the ambiguous combination of a major third and minor third interval. The confusion that eventually leads to Billy's demise is represented by intervals of a perfect fourth, associated with Claggart. During the course of the opera, Vere's music is infiltrated by Claggart's motives. Billy is represented in the opera by the woodwind instruments, Vere by the strings and Claggart by the brass instruments. / Thesis (M.Mus.)--North-West University, Potchefstroom Campus, 2006.

Made available in DSpace on 2014-06-11T19:28:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2004-04Bitstream added on 2014-06-13T20:58:36Z : No. of bitstreams: 1 elisei_cca_me_guara.pdf: 1405191 bytes, checksum: 4108c22cd51274171b8447b8d08e9498 (MD5) / Universidade Estadual Paulista (UNESP) / Foram caracterizados os comportamentos eletroquímicos e avaliadas as resistências à corrosão das ligas aeronáuticas 2024-T351 e 7050-T7451 em soluções aquosas de cloreto contendo cromato, molibdato e tungstato. Foram realizados ensaios de corrosão não-eletroquímicos de imersão prolongada acompanhados de análise metalográfica de superfície por microscopia óptica e identificação dos produtos de corrosão por difratometria de raios-X. A análise quantitativa de superfícies das ligas após a imersão, indica que os pites formados têm áreas médias similares. Os pites são mais largos do que profundos e de geometria, predominantemente, cônica ou quase-cônica e irregular. Em todos os produtos de corrosão de cada liga foi encontrado hidróxido de alumínio, em suas diferentes formas cristalinas. Medidas de perda de dureza, como uma conseqüência da deterioração superficial, também foram determinadas. Além disso, ensaios eletroquímicos como medidas de potencial em circuito aberto, curvas de polarização e voltametria cíclica complementaram este estudo. Em meio aerado os resultados obtidos mediante medidas eletroquímicas são consistentes com aqueles obtidos nos ensaios de imersão, em particular o efeito do CrO42- e do MoO42-. O WO42- mostrou-se agressivo em períodos prolongados de imersão. Apesar dos ensaios revelarem uma redução parcial de MoO42- em ambas as ligas, o efeito desse oxi-ânion parece ser diferente sobre cada liga. Em meio desaerado as ligas apresentam passivação em todos os eletrólitos. A adição dos oxi-ânions não modificou significativamente o potencial de pite para a liga 7050, enquanto que para a liga 2024 ele foi deslocado levemente para valores mais positivos. / It has been characterized the electrochemical behavior and evaluated the 2024-T351 and 7050-T7451 aircraft alloys corrosion resistance in chloride aqueous solutions containing chromate, molybdate and tungstate. It has been carried out non-electrochemical long immersion corrosion testings accompanied by surface metalography analysis achieved by light microscopy and corrosion products identification by X-ray difratometry. Surfaces quantitative analysis upon the alloys after immersion, indicates that formed pits have similar average area. Pits are widther than deeper and own predominantly a conical or quasi-conical and irregular geometry. In all corrosion products of each alloy it has been found aluminum hydroxide in its different crystalline ways. Hardness loss measurements have also been determined. In addition, electrochemical testings such as open circuit potential measures, polarization curves and cyclical voltammetry have completed this study. In aerated means the obtained results before electrochemical mesurements are similar to those obtained in the immersion tests, in particular CrO42- and MoO42- effects. WO42- has been found to be aggressive in very long immersion period. Though tests display a MoO42- partial reduction in both alloys, this oxi-anion effect seems to be different upon each alloy. In de-aerated means alloys present passivation in all eletrolytes. Oxi-anion addition has not changed significantly pit potential for 7050 alloy, while for 2024 alloy it has been dislocated, slightly, for more positive values.

The thesis aims to determine the effectiveness of the Church of England’s (C. of E.) guidance for writing statements of significance. It examines the adoption of ‘significance’ as a system for deciding what elements of the historic environment should be conserved and in what way. The growing influence of significance-theory will be examined along with the emerging practice of defining significance through the identification of multiple values. The question of who should be involved in the process of identifying significance will also be discussed in the context of the increasing importance of public engagement both politically in the U.K. and in the international conservation world. The issues which make the C. of E. a separate case from the secular system of conservation will be examined including its separate system of building consent, different conservation principles, the particular issues surrounding historic buildings which remain in their original use and the C. of E.’s emphasis on voluntary, pubic involvement. The thesis uses St. John the Baptist, Plymtree a parish church in East Devon as a case study in order to test the effectiveness of the C. of E.’s current methodology for determining significance. Before this examination takes place the historic development of Plymtree church is examined in the context of the regional and national background. In addition to assessing the significance of Plymtree church according to the C. of E. methodology the church will also be appraised using three other methodologies for assessing significance; two secular methods and the Churches Conservation Trust methodology. The results of these four appraisals will then be analysed for their strengths and weaknesses and a new methodology created which reflects these results.

Magister Pharmaceuticae - MPharm / In this study, new solid supramolecular derivatised forms of bis(adamantine-1-aminium) carbonate (ADTCO3) were prepared. ADTCO3 is a derivative of amantadine used for Parkinson’s disease and has antiviral properties against influenza-A, dengue fever and pharmacological activity towards Parkinson’s disease. The new forms prepared were polymorphic and co-crystal forms of ADTCO3. Polymorphism is a phenomenon where the ability of a substance to exist in two or more crystalline forms occurs when crystallised under different conditions and co-crystallization is the process of formation of multicomponent crystals of a drug substance. New solid forms often display different mechanical, physicochemical and thermal properties that can remarkably influence the bioavailability, hygroscopicity and stability of active pharmaceutical ingredients (APIs). For the formation of polymorphs of ADTCO3, techniques such as dry grinding, solvent-drop grinding, co-precipitation, sublimation and vapour diffusion were applied. For the development of co-crystals and/or complex formation, ADTCO3 was treated in combination with ten selected co-formers viz; benzoic acid, 4-hydroxybenzoic acid, cinnamic acid, 4-hydroxycinnamic acid, succinic acid, tartaric acid, salicylic acid, L-glutamic acid, citric acid monohydrate and L-glutaric acid using similar techniques as applied in the polymorphism study. The first four co-formers were selected for their potential biological activity and the latter six were selected for their generally regarded as safe (GRAS) status. All products were isolated and characterized using different analytical techniques to assess the thermal behaviour of the products by hot stage microscopy (HSM), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). FTIR spectroscopy and proton-nuclear magnetic resonance (1HNMR) were used to identify and determine the purity of the parent compounds and the modified forms. X-ray powder diffraction was used to determine the formation of a new phase and single crystal X-ray diffraction was applied at the initial stages to identify ADTCO3 by its unit cell parameters. Furthermore, the Cambridge Structural Database (CSD) and other resources were used to generate information on the molecular structures of all elucidated parent compounds, their polymorphs and reported co-crystals. Four different polymorphic forms of ADTCO3 were identified (viz. ADTCO3 Forms I to IV) and sixteen co-crystals (viz. ADTCO3BA1 to ADTCO3BA5, ADTCO3HBA, ADTCO3CIN, ADTCO3HCIN, ADTCO3SUC, ADTCO3LTTA, ADTCO3SA, ADTCO3CA, ADTCO3GLA, ADTCO3GA) were synthesised. Of the sixteen co-crystals 5 were identified as ADTCO3BA “salt” co-crystal polymorphic forms and 2 as ADTCO3SUC co-crystal polymorphic forms. Two solvated “salt” co-crystal forms were also identified, namely; ADTCO3GLA and ADTCO3LTTA. ADTCO3GLA had a mass loss of 10.3% (n = 2.4) and ADTCO3LTTA had a mass loss of 5.25% (n = 0.86). Finally, the rest of the co-crystals ADTCO3HBA, ADTCO3CIN, ADTCO3HCIN, ADTCO3SA, ADTCO3CA and ADTCO3GA all crystallised as “salt” co-crystals.

The energy demands by the industrial world are continuing to rise, while the rate of new oil discoveries is falling. Within the next 30 years, available petroleum supplies are likely to fail to meet the demand, and oil will no longer be able to serve as the world’s major energy source. Coal, being relatively abundant worldwide and potentially adaptable for use in existing plants that have been engineered for petroleum use, can serve as an inexpensive substitute for, or successor to, the more expensive oil fuels in use today. Graphitisable carbon is one of the high-value products from petroleum as its value lies partly in the nuclear industry. Making graphitisable isotropic carbon from well-purified coal is therefore a primary motivation for this study. However, its purity is far too low. Substantial purification is obtained by dissolving the organic part of coal in dimethylformamide with the addition of a little alkali. Results indicated that more than 90% of the organic part of a 10% ash flotation product dissolved in N, N dimethylformamide on addition of 10% NaOH. The bulk of the impurities are removed by centrifugation and the dissolved organic material is recovered by water precipitation. Subsequently, the ash level is lowered from 10% in the coal to < 1.60% in the coal extracts at a washing efficiency of 33 %. The addition of Na2S (the molar ratio of NaOH to Na2S was 1:1) lowered the ash level further to 0.70%. The coal extract solution obtained showed an absorbance of 1.00 with an organic content of 8%. However, addition of sodium sulphide to the extraction medium at 25 ± 1oC lowered the organic content to 5.6%. At high temperature of 90 ± 2oC, the organic content was further lowered to 2.6% with subsequent loss in colour. The coal extract obtained by water precipitation showed low C/H atomic ratio on the addition of S-2. Nucleophiles such as cyanide, thiosulphate made no substantial change to the hydrogen content nor the degree of extraction. On coking by step heating under nitrogen to 480oC at a rate of 10oC min-1 for 1h, then to 900oC with a soaking period of 2h, the coal extracts melt, then reorganise into a liquid crystal phase around 500oC, which then solidifies into a semi-coke on further heat treatment. The heat-treatment of the coal extracts produced 75% carbon yield. When polished specimens of the cokes were observed by reflectance microscopy, flow textures with domain sizes of a few to many microns were observed. Isotropic, poorly graphitising cokes showed little or no structure. Anisotropic cokes were produced when these domains of liquid crystal grew and coalesced. The cokes were found to be highly graphitisable. However, in the heat treated coal extracts prepared at high temperature, the liquid crystal domains were graphitisable but appeared not to have coalesced. Nevertheless, the random orientation of the domains allowed isotropic blocks to be formed with extremely low crystallinity. The precursors that form these liquid crystals are generally materials known to have a high aromatic carbon content. The precursors that form these liquid crystals are generally materials with a high purity and aromatic carbon content, and low in heteroatoms. Optical microscopy of the polished samples prepared at 90  2oC revealed surfaces with much less ordered coke, having smaller crystalline domains than the heat–treated coal extracts derived at room temperature. Essentially, isotropic graphites were obtained. Addition of S-2 produced an extensive flowing texture, and a highly crystalline domain cokes. The carbon yield lowered. The graphitisability of the carbon improved. The X-ray diffraction data on the graphitised carbon showed that the degree of graphitisation decreased in the following order: high S-2 coal extracts derived at room temperature (GSF-25RT) > high S-2 coal extracts derived at high temperature (GSF-25HT) and no S-2 coal extracts derived at room temperature (GSF-0RT) > no S-2 coal extracts derived at high temperature (GSF-0HT), corresponding to 79 > 75% and 67 > 25% respectively. The interlayer spacing (d002 -value) of the graphites follows the order GSF-25RT (3.37Å) < GSF- 25HT (3.38 Å) and GSF-0RT (3.38 Å) < GSF-0HT (3.42 Å). Subsequently, the Raman spectroscopy, consistent with the X-ray diffraction data, showed the ratio of the d-peak (degenerate) to g-peak (graphitic) in the order: GSF-0HT < GSF-0RT and GSF-25HT < GSF-25RT, corresponding to 1.26 <1.75 < and 6.7 < 7.0 respectively. Because the quality of the coke depends on the nature and quality of the starting material, addition of the carbon additives in the starting material prior heat-treatment affected the flow texture of the coke. The carbon black, which has a spherical shape, forms aggregates that disperse much more easily than the flat chains of aggregates of acetylene black. The difficulty in dispersing the carbon additives was, however, overcome by using a high-shear mixer. Analysis of the coal extracts revealed that the hydrogen content in the coal extracts decreased linearly on addition of the carbon additives, favoring dehydrogenative polymerisation. The addition of carbon additives in the coal extract solution produced an isotropic carbon on heat treatment. Optical microscopy of the resin-mounted cokes revealed decreasing size of the crystalline domain with increasing dosage of the carbon additives. The optimum amount of carbon additives required was found no to exceed 0.44%. Beyond this threshold, the anisotropy of the cokes could not be observed through the resolution of the optical microscope. In addition, the amounts of volatiles released were found to decrease with increasing dosage of the carbon additives. At low dosage of the carbon additives, the heat-treated coal extracts produced graphitisable isotropic carbon with low level of crystallinity. However, at high dosage of the carbon additives, the cokes did not graphitise. The temperature of graphitisation decreased from 2976 to 2952oC with increasing dosage of the carbon additives. The decreasing order of graphitisation was 69 > 61 > 62%, corresponding to 0.44 > 0.88 > 1.60 acetylene black. With the addition of carbon black, the decreasing order of graphitisation was 57.7 > 56.5 > 51.5%, corresponding to 0.44 > 0.88 > 1.60 wt % respectively. The interlayer spacing d002, increased in the same order, suggesting a shift towards a turbostratic and formation of a poorly graphitised, and turbostratic carbon. Raman spectroscopy revealed that the intensity ratio R of the g to the d peak decreased with increasing dosage of the carbon additive. Cokes produced from the coal extracts prepared at 25oC but without S-2 showed also a remarkable degree of flow texture. Its crystalline domain units were relatively small. The resin-mounted coke samples observed under an optical microscope (objective x 25) showed reduced flow texture with the addition of carbon black. The graphitisability of the resultant cokes also decreased on addition of carbon black. The optimum dosage observed for reducing the flow texture without reducing the crystallinity was found to be < 0.22%. Improved degree of graphitisation of the carbon was studied on addition of iron (lll) compounds. Iron (lll) compounds showed a promising improvement in the graphitisability of the carbon when added in small amounts. The intracellular hard carbon is converted to soft carbon, thereby improving the degree of graphitisation. The overall effect was a more isotropic graphitic carbon but the degree of graphitisation obtained was far too low: on addition of 1% and 3% (by wt) of iron (lll), the compounds were 21% and 27% respectively. Oxygen intrusion into the precursor’s coal material prior to heat treatment is thought to have inhibited the degree of graphitisation. Increasing the amounts of the iron (lll) compound and prohibiting the intrusion of oxygen during mixing could improve the graphitisability of carbon. However, the optimum amount to be used remains an important subject to be explored in future. / Thesis (PhD (Chemistry))--University of Pretoria, 2007. / Chemistry / unrestricted