Thesis (Masters Diploma (Technology)--Cape Technikon, Cape Town,1993 / Various experimental and established membranes were tested on industrial effluents. Ultrafiltration, reverse osmosis and nanofiltration membranes were used in various applications. Research was done on aspects such as the cleaning of fouled membranes, production quality control and process development. Polyvinyl alcohol ultra-thin-film reverse osmosis membranes were manufactured for the desalination of brackish water to a potable standard. The membranes were manufactured in the tubular configuration. Experimental ultrafiltration, reverse osmosis and nanofiltration membranes were tested on cooling water blowdown on a laboratory-scale. On-site testing was done directly on the effluent at a later stage. A s!udy was also conducted to determine the effect of gel-polarization on membrane performance. The gel-layer model was used to predict the limiting flux of specific membranes. Membrane processes were also applied in the fractionation of wine-lees to provide usable by-products such as yeast cells and potassium bitartrate. Ultrafiltration membranes operated in diafiltration mode were used to "wash" the slurry at different solid concentrations. The bitartrate-rich permeate collected from ultrafiltration was then concentrated using reverse osmosis and nanofiltration to allow subsequent precipitation of the product.

abstract: Telomerase is a unique reverse transcriptase that has evolved specifically to extend the single stranded DNA at the 3' ends of chromosomes. To achieve this, telomerase uses a small section of its integral RNA subunit (TR) to reiteratively copy a short, canonically 6-nt, sequence repeatedly in a processive manner using a complex and currently poorly understood mechanism of template translocation to stop nucleotide addition, regenerate its template, and then synthesize a new repeat. In this study, several novel interactions between the telomerase protein and RNA components along with the DNA substrate are identified and characterized which come together to allow active telomerase repeat addition. First, this study shows that the sequence of the RNA/DNA duplex holds a unique, single nucleotide signal which pauses DNA synthesis at the end of the canonical template sequence. Further characterization of this sequence dependent pause signal reveals that the template sequence alone can produce telomerase products with the characteristic 6-nt pattern, but also works cooperatively with another RNA structural element for proper template boundary definition. Finally, mutational analysis is used on several regions of the protein and RNA components of telomerase to identify crucial determinates of telomerase assembly and processive repeat synthesis. Together, these results shed new light on how telomerase coordinates its complex catalytic cycle. / Dissertation/Thesis / Ph.D. Chemistry 2014

Orientador: Orlando Fontes Lima Junior / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-23T21:07:50Z (GMT). No. of bitstreams: 1 Avoleta_AmandaQuintal_M.pdf: 2120211 bytes, checksum: 1342fc21a341b82751b3e3bd9bf99c33 (MD5) Previous issue date: 2013 / Resumo: O objetivo desse trabalho centrou-se em desenvolver um modelo para dimensionamento do número de embalagens do tipo "múltiplas viagens" (multiway), em uma cadeia de suprimentos de laço fechado. Tais embalagens retornam à cadeia depois de acondicionarem o produto ao seu destino final. Em seu retorno passam por um processo de manutenção (reparo, limpeza), para voltarem a sua forma original e, então, são estocadas para próximo uso. Uma embalagem, em seu ciclo de acondicionamento do produto, está sujeita a incertezas associadas aos seguintes fatores: demanda do produto final; tempo de viagem com o produto; tempo de permanência no ponto de consumo; tempo de retorno ao ponto de reuso; tempo de manutenção para o próximo uso; e sua indisponibilidade afeta significativamente o nível de atendimento ao cliente. Embora exista um vasto material sobre o gerenciamento da cadeia direta, os estudos sobre cadeia reversa são mais raros e se prendem principalmente a estudos de configurações para o fluxo em retorno e seus custos. No dimensionamento do número ideal de embalagens para atendimento do consumidor, com um nível adequado de suprimento, não são encontrados trabalhos que considerem a questão da aleatoriedade dos tempos de viagem relacionada à gestão dessas embalagens. A proposta deste trabalho consistiu em estabelecer um procedimento para os tratamentos dos dados, visto que são aleatórios, e disponibilizar um modelo simulação que auxiliasse a gestão de cadeias com embalagens multiway. A aplicação é feita em uma cadeia voltada para o comércio de flores, pela necessidade de acondicionamento destas em embalagens que as protejam de danos durante o período de manipulação e viagens. Por questões econômicas, são utilizadas embalagens retornáveis que, após serem utilizadas, reintegram-se à cadeia de suprimentos, tornando-a uma cadeia de suprimentos de laço fechado / Abstract: The purpose of this research was to develop a model to quantify the number of multiway packaging, which involves several journeys within a closed loop supply chain. This type of packaging returns to the chain after the goods reach their final destination. Subsequently the packaging proceed to a maintenance process (repair, cleaning) in order to return to its original condition and then be stocked for future use. The storage cycle of a package is subject to uncertainties associated to several factors such as the demand of the final product; the time spent on carriage; the dwell time at the consumption site; the time spent until it returns to the reusing site, and the time of maintenance for next use. The unavailability of the package affects meaningfully the customer attendance level. Although there is a wide set of studies on managing direct chains, studies about the reverse logistics are scarcer and mostly focused on the return process flow configuration and its costs. Regarding the definition of the ideal number of packaging to assist customers with proper supplies, it has neither been found any study that considers the randomization of the time spent on the transportation nor on the management of these packages. The aim of this analysis was to establish a protocol to manipulate data, considering it as being arbitrary, and then to release a simulation model which would benefit managing the multiway packaging chain. The application was done in a chain of a flower business, due to their need of keeping their product in a suitable package that had to protect it from damages during transportation and handling. For economical reasons, returnable packages that can be reinstated to the supply chain are used so that the process is turned into a closed loop / Mestrado / Transportes / Mestra em Engenharia Civil

The task to this thesis has been to create an application, Katana-databas 1.0, for analysing c-code. The generated output gets stored in a data structure which content in the end of the program run gets written in a textfile which gets used by Katana. It's a tool for reverse engineering, developed by Johan Kraft at Mälardalens institute. Katana-databas has got the following limitations. (1) It can only handle preprocessed files, meaning it doesn't contain any rows beginning with "#". (2) Only complete files can be handled. (3) No references to unknown functions or variables are allowed. (4) A further limitation is that the application can't handle any ADT's. It can only handle primitive types. (5) Finally the application is only written for pure c-code, and thus doesn't handle code written C++. The task has been solved by creating an automatically generated lexer with Flex and Bison rules in Visual Studio. There after a limited parser has been developed which purpose is to process the lexemes which the lexer generates. The underlying causes for the thesis is to replace Understand with Katana-databas. Katana has this far used the database in Understand, but it contains closed source code. What is seeked is open source code, which Katana-databas is based on. / Programmeringsuppgiften till detta arbete har bestått i att skapa en applikation, Katana-databas 1.0, för analys av C-kod. Utflödet som applikationen skapar sparas i en datastruktur vars innehåll i slutet av programkörningen skrivs ut i en textfil som används av Katana. Det är ett verktyg för reverse engineering, utvecklat av Johan Kraft på Mälardalens högskola. Katana-databas har fått följande begränsningar. (1) Den kan bara hantera filer som är preprocessade, dvs. den innehåller inga rader som inleds med ”#”. (2) Endast kompletta filer kan hanteras. (3) Inga referenser till okända funktioner eller variabler är tillåtna. (4) En ytterligare begränsning är att applikationen inte kan hantera ADT:er. Den kan bara hantera primitiva typer. (5) Tillsist är applikationen endast skriven för ren c-kod, och klarar således inte av att hantera kod skriven i C++. Uppgiften har lösts genom att skapa en automatgenererad lexer med Flex och Bisonrules i Visual Studio. Därefter har en limiterad parser utvecklats vars syfte är att bearbeta de lexem som lexern genererar. Det bakomliggande syftet med arbetet är att ersätta Understand med Katana-databas. Katana har hittills använt sig av databasen i Understand, men den består av sluten källkod. Det som eftersträvas är öppen källkod, vilket Katana-databas baseras på.

Over the years, packed malware have started to appear at a more rapid pace.Hackers are modifying the source code of popular packers to create new typesof compressors which can fool the Anti Virus software. Due to the sheer vol-ume of packer variations, creating unpacking scripts based on the packer’ssignature has become a tedious task. In this paper we will analyse genericunpacking techniques and apply them on ten popular compression software.The techniques prove to be successful in nine out of ten cases, providing aneasy and accessible way to unpack the provided samples

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Steel tubular structures are becoming more widely used in recent years because of their excellent structural performance as well as appearance. For structures with steel hollow section (SHS) columns and concrete filled tubular (CFT) columns, several types of joint may be used to connect to wide flange beams. The topic of this research is a relatively new type of joint, the 'reverse channel' connection, in which the legs of a channel are welded to the tube thus converting the closed tubular column into an open section for connection purpose. However, since tubular columns have only recently become more popular in frames, there is a lack of research to quantify the moment-rotation characteristics of connections between I beams and tubular columns. A total of eight tests on loaded steel beam to RHS column connections using reverse channel and endplate, up to collapse, were carried out. The objectives of these tests were to investigate the effects of different connection details on connection performance and to provide experimental data for validation of numerical simulations. Validation of numerical modelling was carried out to check accuracy of the numerical simulation model developed using the general finite element package ABAQUS. The validated ABAQUS model was then used to perform various parametric studies to provide insight into structural behaviour. A systematic approach to quantify the load carrying capacity of the reverse channel web and the column face were adopted based on yield line theory. This thesis presents the derivation and validation of the analytical approach. The moment resistance of the whole connection can be obtained by assembling all the components together. A procedure for calculation was proposed to provide feasibility for designer and the analytical results were compared with the test results.

The aim of this study was to investigate the effect of reverse shoes, partial dorsal hoof wall removal and polystyrene solar support on the biomechanics of the front hoof of the horse. Laminitis is a systemic syndrome that ultimately affects the sensitive lamellae and papilla of the hoof, causing severe pain, and often leading to disruption of the lamellae-hoof wall interface. Degeneration of the lamellar interdigitation occurs and the distal phalanx (P3) separates from the hoof wall. This can cause P3 to rotate towards the sole and, in more severe cases, P3 separates totally from the hoof wall and sinks downwards. Chronic laminitis usually results in the end of the animal’s athletic career and may lead to humane destruction During an in vitro study, three clinically healthy horses were euthanased and their dismembered forelimbs were used. A reverse shoe was applied and three polystyrene pads with a density of 32 kg/m3, thickness of 60mm and wedges of 66%, 50% and no wedging, respectively, were used in this study. Fuji Prescale Super and Ultra Super Low-Pressure film was used to indicate the pressure distribution of the polystyrene on the solar surface of the hoof. Two load cells were used to measure the load borne by the hoof wall and the solar area, respectively. A constantly increasing force with a maximum of 66% of the bodyweight of the horse was applied to the amputated limb by means of a tensile testing machine. A total of four experiments were done on each limb. The results of this investigation showed that for all three of the polystyrene paddings, approximately 75 - 80% of the total load applied was borne by the solar area. The colour changes on the pressure film showed that most of the load of the 50% and 66% wedged polystyrene was borne by the palmar half of the solar surface, and less pressure by the dorsal half. For no wedging, the pressure distribution over the solar surface was even. The reverse shoe with the 66% and the 50% wedged polystyrene pads was shown to be useful in distributing the pressure to the palmar area of the sole. During an in vivo study, the effect of different densities (32 kg/m3, 24 kg/m3 and 16 kg/m3) and different thicknesses (100mm and 60mm) of polystyrene padding, with a wedge of 50%, on the load distribution of the solar surface and the hoof wall was investigated. Compression of polystyrene over time and the effect thereof on the load distribution was determined. The front hooves of three clinically healthy horses with a mean bodyweight of 551 kg, were trimmed and shod with reverse shoes. Reference data was recorded with only the reverse shoes on the hooves. Further data recording was done for the different polystyrene pads. Data was recorded for 4 seconds with a frequency of 50Hz. Between the treatments, the horses walked for 5 minutes on a concrete surface. This procedure was repeated 5, 10 and 15 minutes after application of the pads. All the results of the solar pads used in the in vivo study showed a hyperbolic tendency in which the initial load was high and then diminished with time. Initially, treatments 5 (32 kg/m3 x 60 mm) and 3 (16 kg/m3 x 60mm) proved to be the better treatments, but after 15 minutes no significant different was found between the treatments. From the observations made during the experimental procedure, the 32 kg/m3 x 60mm (treatment 5) compressed to a more dense and rigid end-product than the 16 kg/m3 x 60mm (treatment 3). The compressed pad of treatment 3 was more elastic and may have contributed positively to reducing the compression of the pads on the blood vessels underneath P3. Observations made during the experimental procedures indicated that polystyrene with a thickness of 100mm, is not recommended. This polystyrene was very uncomfortable for the horse immediately after application. Some polystyrene compressed outside the solar surface and was therefore not adequate for the object of the study. It was concluded that polystyrene pads with densities of 32kg/m3, 24kg/m3 and 16kg/m3 and thicknesses of 100mm and 60mm would prove similar support for the remainder of the period that they were applied follow a variable compression phase of less than 15 minutes. Further research need to be done to investigate the effect of the polystyrene pad on the solar surface for a longer period. Copyright / Dissertation (MSc)--University of Pretoria, 2009. / Companion Animal Clinical Studies / unrestricted

abstract: Managing water resources has become one of the most pressing concerns of scientists both in academia and industry. The reverse osmosis (RO) water treatment process is a well-researched technology among the pressure driven processes to produce potable water. RO is an energy intensive process and often RO membranes are susceptible to fouling and scaling that drives up operational cost and hinder the efficiency. To increase the performance of RO membranes the feed water is pretreated to remove pollutants before desalination. This work aims to fabricate pretreatment membranes to prevent the effects of fouling and scaling by introducing hydrophilic character to membrane. This work explores electrospinning, a cost-effective and scalable technique, to blend two polymers into a nonwoven membrane comprised of fibers ~100 nm - 10 µm in diameter. A rotary drum collector holding the mat was used to simultaneously collect the electrospun hydrophobic poly(vinyl chloride) (PVC) and hydrophilic poly(vinyl alcohol) (PVA) fibers from two separate solutions. The hydrophilicity of the resulting membrane was tuned by controlling the relative deposition rate of PVA onto the co-spun mat. Fiber diameter and morphologies were characterized by scanning electron microscopy, and Fourier-transform infrared spectroscopy and Confocal fluorescence microscopy further confirmed the presence of both polymers. Moreover, a rigorous analysis to map the PVA/PVC concentration was established to accurately report the relative concentrations of the two polymers on the co-spun mat. After electrospinning, the PVA in the co-spun mats were cross-linked with poly(ethylene glycol) diacid to impart mechanical strength and tune the porosity. EDS analysis revealed inconsistencies in the mass deposition of both polymers suggesting an improvement in the current experimental design to establish a meaningful relationship between PVA concentration and hydrophilicity. However, tensile test revealed that co-spun mats with high mass flow ratios of PVA possessed high mechanical strength showing a significant improvement in the Young’s Modulus. Furthermore, the co-spun mats were challenged with filtration experiments expecting a positive correlation of flux with PVA concentration. But it was found that with increased concentration, crosslinked PVA constricted PVC fibers minimizing the pores causing a lower flux and a dense membrane structure suitable for filtration. / Dissertation/Thesis / Masters Thesis Chemical Engineering 2020

This thesis deals with water reclamation and water reuse in the South African water supply context. The overall objective of the study is to assess the potential role and feasibility of reverse osmosis as a water reclamation process. In order to achieve this objective a number of separate desk, laboratory and pilot plant studies were conducted. It was concluded from the first desk study that a significant potential role exists for reverse osmosis in the South African water economy, mainly for the treatment of industrial effluents and, in the longer term, for the reclamation of water from sewage effluents and for the treatment of effluents and recycled water in indirect water reuse situations. A cost analysis showed that reverse osmosis could become economically viable in some water reuse situations in the near future provided that a productive membrane life of about three years can be achieved and that membrane fluxes can be maintained at design rates. These findings indicated the need for a pilot plant study to determine the effects of pretreatment and membrane cleaning on flux levels and rejection. A 50 m³/d pilot plant was designed and operated for a period of about six months from which it was concluded that acceptable flux levels can be maintained in tubular reverse osmosis plants treating well-oxidized activated sludge effluent with and without extensive pretreatment, provided both chemical and physical cleaning methods are employed. The desk study on the rejection of contaminants by reverse osmosis membranes indicated the need for a simple model that can be used to predict the removal of organic compounds of interest in water reclamation applications. It was concluded from a fundamental laboratory study, which included the evaluation of existing membrane models against laboratory data, that the solvophobic theory can be adapted in a simplified form to predict the transport of dissolved organic compounds in relatively non-polar reverse osmosis membranes. Based on reverse osmosis, diffusion, sorption and desorption data a mechanism is, furthermore, proposed for the transport of phenol in different membranes.