A polymer-based composite reinforced with a mixture of Ni and Al powders was investigated as an example of a multifunctional structural energetic material. Micron-sized Ni powder, nano/micron-sized Al powders, and Teflon or epoxy were fabricated as bulk materials by pressing or casting. The thermally initiated reaction response of these materials was evaluated using differential thermal analysis coupled with x-ray diffraction. The analyses showed evidence of thermally initiated reactions between Ni and Al powders, as well as between Ni+Al and Teflon. Nano-sized Al powder showed a preference for reaction with Teflon over Ni, while micron-sized Al reacted strongly with Ni regardless of the presence of a binder. Teflon was shown to be very reactive with the Ni+Al/nano Al mixture, whereas epoxy was not reactive with the metallic powders, and also inhibited reaction between Ni and nano Al. The structural/mechanical behavior of these materials was evaluated using elastic and plastic property measurements via static and dynamic compression tests. Dynamic mechanical testing using reverse Taylor anvil-on-rod impact tests combined with velocity interferometry gave qualitative and quantitative information about the transient deformation and failure response of the composites. The material containing 20wt% epoxy and nano-sized Al powder showed the most superior mechanical properties in terms of elastic modulus and static and dynamic compressive strength. The addition of Ni and Al powders to the epoxy matrix increased the strength of the composites, and their tendency toward brittle fracture, as evidenced by Ni particle pullout in SEM analysis. The results illustrate that nano-sized Al particles provide significant enhancement to strength of epoxy composites, but at the expense of reactivity. The nano-Al particles get dissociated from the Ni and Al mixture and swept into the epoxy, generating a nano-Al containing epoxy matrix with embedded Ni particles. The chemical reactivity of the system is thus sacrificed as contacts between Ni and Al powders are minimized. A mixture of nano-sized Ni and Al particles may however provide the best combination of high strength and reactivity.

The mechanical characterization of the interfacial shear strength (IFSS) of carbon nanotube (CNT) coated carbon fibers and the interlaminar fracture toughness of woven fabric carbon fiber/epoxy composites toughened with CNT/epoxy interleave films is presented. The deposition of multiwalled carbon nanotubes (MWCNT) onto the surface of carbon fibers through thermal chemical vapor deposition (CVD) was used in an effort to produce a graded, multifunctional interphase region used to improve the interfacial strength between the matrix and the reinforcing fiber. Characterization of the IFSS was performed using the single-fiber fragmentation test. It is shown that the application of a MWCNT coating improves the interfacial shear strength between the coated fiber and matrix when compared with uncoated fibers. The effect of CNT/epoxy thin interleave films on the Mode I interlaminar fracture toughness of woven fabric carbon/epoxy composites is examined using the double-cantilever beam (DCB) test. Initiation fracture toughness, represented by critical strain energy release rate (GIC), is shown to improve over standard un-toughened composites using amine-functionalized CNT/epoxy thin films. Propagation fracture toughness is shown to remain unaffected using amine-functionalized CNT/epoxy thin films with respect to standard un-toughened composites.

Coupling between the electric field, magnetic field, and strain of composite materials is achieved when electro-elastic (piezoelectric) and magneto-elastic (piezomagnetic) particles are joined by an elastic matrix. Although the matrix is neither piezoelectric nor piezomagnetic, the strain field in the matrix couples the E field of the piezoelectric phase to the B field of the piezomagnetic phase. This three-phase electro-magneto-elastic composite should have greater ductility and formability than a two-phase composite in which E and B are coupled by directly bonding two ceramic materials with no compliant matrix. A finite element analysis and homogenization of a representative volume element is performed to determine the effective electric, magnetic, mechanical, and coupled-field properties of an elastic (epoxy) matrix reinforced with piezoelectric and piezomagnetic fibers as functions of the phase volume fractions, the fiber (or particle) shapes, the fiber arrangements in the unit cell, and the fiber material properties with special emphasis on the symmetry properties of the fibers and the poling directions of the piezoelectric and piezomagnetic fibers. The effective magnetoelectric moduli of this three-phase composite are, however, less than the effective magnetoelectric coefficients of a two-phase piezoelectric/piezomagnetic composite, because the epoxy matrix is not stiff enough to transfer significant strains between the piezomagnetic and piezoelectric fibers.

Undesirable cabin noise has an adverse physiological effect on passengers and crews in an aircraft. In order to reduce the noise level, a passive approach using a truss-core sandwich (TCS) panel as a sound insulator is proposed. Design guidelines and analysis methodologies were developed in order to explore the vibro-acoustic characteristics of TCS structure. Its sound isolation properties can be thereby assessed. Theoretical analyses show that the transmission-loss and sound radiation properties of a TCS structure can be represented by the root-mean-square velocity of its surface, and a beam structure analysis is sufficient to reveal many of the important aspects of TCS panel design. Using finite element analysis, a sensitivity study was performed to create design guidelines for TCS structures. Transmission-loss experiments show that the analytical and numerical analyses correctly predict the trend of TCS structure’s vibro-acoustic performance.

Undesirable cabin noise has an adverse physiological effect on passengers and crews in an aircraft. In order to reduce the noise level, a passive approach using a truss-core sandwich (TCS) panel as a sound insulator is proposed. Design guidelines and analysis methodologies were developed in order to explore the vibro-acoustic characteristics of TCS structure. Its sound isolation properties can be thereby assessed. Theoretical analyses show that the transmission-loss and sound radiation properties of a TCS structure can be represented by the root-mean-square velocity of its surface, and a beam structure analysis is sufficient to reveal many of the important aspects of TCS panel design. Using finite element analysis, a sensitivity study was performed to create design guidelines for TCS structures. Transmission-loss experiments show that the analytical and numerical analyses correctly predict the trend of TCS structure’s vibro-acoustic performance.

Bakalauro darbas ,,Mados pinklės“ – tai daugiafunkcinių krepšių grupė, kurią sudaro du krepšiai: kelioninė rankinė bei kuprinė, kurie užtrauktukų pagalba transformuojasi į atskiras krepšių-rankinių grupes. Iš viso komplektą sudaro 5 rankinės, krepšys išsiskaido į tris arba dvi rankines, o kuprinė į dvi. Toks išskirtinis komplektas gali būti demonstruojamas įvairiuose mados renginiuose, eksponuojamas galerijose ar pavyzdžiui individualios aksesuarų parduotuvės vitrinoje. Taip pat tokie gaminiai gali būti pateikiami verslo asociacijų pristatymuose. Juos pakoregavus ir supaprastinus konstrukciją, būtų galima pritaikyti tiražinei gamybai. / Bachelor‘s work „Fashion trap“- group of multifunctional haversacks, which are made of two haversacks: travel handbag and bag, which can be transformed into separate groups of haversacks-handbags with the help of zips. The set is made of 5 handbags, the haversack can be divided into three or two handbags and the bag can be divided into two.Such exclusive set can be shown in various fashion events, exhibited in galleries or, for example, in shop windows of individual shop of accessories. Also such kind of products can be presented in presentations of bussiness associations. Adjusting and simplifying construction, it would be possible to apply them to circulating production.

Doctor of Philosophy / Department of Chemical Engineering / Keith L. Hohn / The present work describes the conversion of bio-derived methyl ethyl ketone (MEK) into different useful chemicals. The first part discusses the direct conversion of MEK to butene over supported copper catalysts (Cu-Al₂O₃, Cu-zeolite Y sodium (Cu-ZYNa) and Cu-zeolite Y hydrogen (Cu-ZYH)) in a fixed bed reactor. In this reaction, MEK is hydrogenated to 2-butanol over metal sites, and further dehydrated on acid sites to produce butene. Experimental results showed that the selectivity of butene was the highest over Cu-ZYNa, and it was improved by finding the optimum reaction temperature, hydrogen pressure and the percentage of copper loaded on ZYNa. The highest selectivity of butene (97.9%) was obtained at 270 °C and 20 wt% Cu-ZYNa. Over Cu-Al₂O₃, the selectivity of butenes was less than Cu-ZYNa since subsequent hydrogenation of butene occurred to produce butane. It was also observed that with increasing H₂/MEK molar ratio, butane selectivity increased. However, when this ratio was decreased, hydrogenation of butene was reduced, but dimerization to C₈ alkenes and alkane began to be favored. The main products over 20% Cu-Al₂O₃ were butene and butane, and the maximum selectivity of butene (87%) was achieved at an H₂/MEK molar ratio of five. The lowest selectivity of butene was obtained using Cu-ZYH, reaching ~40%. It was found that the amount of acidity in Cu-ZYH is much higher than in Cu-ZYNa (from (NH₃-TPD) measurements). This could have caused the selectivity of butene to decrease as a result of dimerization, oligomerization and cracking reactions. The second part describes the conversion of MEK to higher ketones in one step using a multifunctional catalyst having both aldol condensation (aldolization and dehydration) and hydrogenation properties. 15% Cu supported zirconia (ZrO₂) was investigated in the catalytic gas phase reaction of MEK in a fixed bed reactor. The results showed that the main product was 5-methyl-3-heptanone in addition to 5-methyl-3-heptanol and 2-butanol with side products including other heavy products (C₁₂ and up). The effects of temperature and the molar ratio of reactants (H₂/MEK) on overall product selectivity were studied. It was found that with increasing temperature, the selectivity to C₈ ketone increased, while selectivity to 2-butanol decreased. The hydrogen pressure plays significant role on the selectivity of products. It was observed that with increasing the H₂/MEK molar ratio, 2-butanol selectivity increased due to hydrogenation reaction while decreasing this ratio leads to increasing aldol condensation products. In addition, it was noted that both conversion and selectivity to the main product increased using a low loading percentage of copper, 1% Cu-ZrO₂. The highest selectivity of 5-methyl-3-heptanone (~63%) was obtained at temperatures around 180 °C and a molar ratio of H₂/MEK of 2. Other metals (Ni, Pd and Pt) supported on ZrO₂ also produced 5-methyl 3-heptanone as the main product with slight differences in selectivity, suggesting that a hydrogenation catalyst is important for making the C₈ ketone, but the exact identity of the metal is less important. The third part discusses the conversion of C₈ ketones to C₈ alkenes and C₈ alkane over a catalyst consisting of a transition metal (Cu or Pt) loaded on alumina (Al₂O₃). These bifunctional catalysts provide both hydrogenation and dehydration functionalities. The main products over 20% Cu-Al₂O₃ were a mixture of 5-methyl-3-heptene, 5-methyl-2-heptene and 3-methyl heptane. However, using 1% Pt-Al₂O₃ the major product was 3-methyl heptane with a selectivity reaching over 97% and a conversion of 99.9 %. Both temperature and the hydrogen pressure play an important role on the conversion of C₈ ketone as well as the selectivity of products (C₈ alkenes and C₈ alkane). Over 20% Cu-Al₂O₃, it was observed that increasing the reaction temperature led to an increase in the selectivity to C₈ alkane as a result of hydrogenation of the C₈ alkene. Also, it was observed that with an increase in H₂/C₈ ketone molar ratio, C₈ alkane selectivity increased. However, when this ratio was decreased, the further hydrogenation of C₈ alkene to C₈ alkane was reduced. The highest selectivity of C₈ alkene (81.7%) was obtained at 220 °C and a H₂/C₈ ketone molar ratio of 2. In addition, an experiment was carried out using a low loading percentage of copper, and it was noted that both conversion and selectivity to the main products decreased over 1% Cu-Al₂O₃. Over 1% Pt-Al₂O₃, C₈ alkane was the major product with different temperatures indicating that further hydrogenation of C₈ alkene was promoted on 1% Pt-Al₂O₃. At low temperature, for both Cu-Al₂O₃ and Pt-Al₂O₃, significant amounts of C₈ alcohols are formed because subsequent reactions do not proceed at a fast enough rate. Also using 1% Pt-Al₂O₃, the main product selectivity is still C₈ alkane with all H₂/C₈ ketone ratios.

Magister Pharmaceuticae - MPharm / The cascade of neurotoxic events involved in the pathogenesis of Alzheimer's disease may explain the inefficacy of currently available treatment based on acetylcholinesterase inhibitors (AChEI - donepezil, galantamine, rivastigmine) and N-methyl-D-aspartate (NMDA) antagonists (memantine). These drugs were designed based on the "one-moleculeone- target" paradigm and only address a single target. Conversely, the multi-target drug design strategy increasingly gains recognition. Based on the versatile biological activities of tacrine, trolox and β-carboline derivatives, the attention they have received as lead structures for the design of multifunctional drugs for the treatment of Alzheimer's disease, and the topology of the active site of AChE, we have designed tacrine-trolox and tacrine-tryptoline hybrids with various linker chain lengths. The aim with these hybrids was to provide additive or synergistic therapeutic effects that might help overcome the limitation of current anti Alzheimer's disease drugs. All synthesized compounds were designed from lead structures (tacrine, tryptoline and trolox) to obtain cholinesterase (ChE) multisite binders and multifunctional AD agents. The study was rationalized by docking all structures in the active site of TcAChE using Molecular Operating Environment (MOE) software before proceeding with the synthesis. ChE inhibition was assessed in a UV enzyme inhibition assay using Ellman's method. Antioxidant activities were assessed using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH.) absorbance assay. The hybrids containing the trolox moiety (compounds 8a-e) showed moderate to high AChE inhibitory activity in the nano to micro molar range (IC₅₀: 17.37 - 2200 nM), BuChE inhibition was observed in the same range (IC₅₀: 3.16 – 128.82 nM), and free radical scavenging activities in micro molar range (IC50: 11.48 – 49.23 µM). These are comparable or slightly higher than their reference compounds donepezil (AChE IC₅₀ = 220 nM), tacrine (BuChE IC₅₀: 14.12 nM), and trolox (DPPH IC₅₀: 17.57 µM). The hybrids with longer linker chain lengths, 6 and 8 carbons (8d and 8e), showed better ChE inhibitory activity than the shorter ones, 2, 3, and 4 carbons (8a-c respectively). This correlates well with literature. Free radical scavenging activities, however, seems not to be significantly affected by varying linker chain lengths. The hybrid compound (14) containing the tryptoline moiety linked with a 7 carbon spacer displayed the best AChE and BuChE inhibitory activity (IC₅₀ = 17.37 and 3.16 nM) but poor free radical scavenging activity. Novel anti-Alzheimer's disease drugs with multi-target neuroprotective activities were thus obtained and hybrid molecules that exhibit good ChE inhibition (8d, 8e and 14) and anti-oxidant (8d and 8e) activity were identified as suitable candidates for further investigation. / National Research Foundation (NRF)

The thesis entitled “This is Africa giving form to the informal” arose from a concern with the growing levels of poverty and unemployment in South Africa and the recognition that small scale, self-generated economic activity provides an important means of survival for the very poor. It acknowledges the positive contributions that informal street trading makes to the urban environment. The dissertation draws upon a study of recently initiated projects that aimed to legitimise informal trading, by integrating it in the built environment. It is also driven by a study of the way in which traders organise, claim and define space in the urban environment. This process can be seen as the way in which traders themselves seek legitimacy. Collectively, case studies revealed a number of key elements necessary for the legitimisation of informal trade. Although the area of the proposed intervention is the Pretoria Station precinct, the study acknowledges that there are universal elements contained in informal trading. These elements establish a set of principles that define the minimal intervention necessary in order to allow opportunities for trade to as many people as possible whilst giving the traders themselves the maximum possible room to manoeuvre. In essence, the approach does not argue for the formalisation or ‘neatening’ of informal activity, but aims to give form to activities frequently regarded as illegal, and to provide street market spaces that can function as essential forms of urban infrastructure (Dewar 1990:xi). / Mini Dissertation (MInt(Prof))--University of Pretoria, 2010. / Architecture / unrestricted

This project investigates the merging of performance apparel from mountain biking and ski touring, based on the emerging trend in combining mountain biking and ski touring as sports. Designing apparel for a combination of sports could contribute to a sustainable change in the outdoor industry by affecting the design thinking, demand and consumerism. All the garments are developed based on the female body and needs. This is shown through both commercial pieces and experimental pieces, with garment shapes that are both similar and not so similar to existing garments. Material placement is based on movement and thermoregulatory responses of the female athlete and plays an important part to achieve both expression and function in the garments. The methodology is explained through five parts; field testing, sketching, prototyping, experimenting and evaluation, which are used both numerical and independently of each other. This resulted in a collection of seven outfits where three of these are produced and the remaining four are illustrated through development, sketches and technical descriptions. Results show suggestions of how a combination between sports could be developed and used. It also shows potential to be developed even further into other various directions.