Orientador: Inez Valeria Pagotto Yoshida / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-04T13:38:50Z (GMT). No. of bitstreams: 1 PachecoeSilva_Viviane_M.pdf: 4530394 bytes, checksum: 571677ec4e372aa12989ee8eada906a1 (MD5) Previous issue date: 2005 / Mestrado / Quimica Inorganica / Mestre em Química

Les mousses rencontrées dans l’industrie pétrolière comptent parmi les mousses les plus complexes et problématiques. Lors de la production du pétrole brut, la présence de mousses stables peut entraîner de gros problèmes dans les équipements de traitement en surface à cause de la dépressurisation et de la nucléation de bulles provenant du gaz naturellement dissous dans le fluide de réservoir. Cette mousse peut rapidement occuper la moitié du volume des séparateurs et provoquer des dommages opérationnels graves, liés à des difficultés de contrôle des niveaux, à l’entraînement de liquide dans la ligne gaz et à l’entraînement de gaz dans la ligne liquide. Le contrôle de ces mousses pétrolières constitue donc un véritable enjeu, et les diverses solutions proposées sont basées sur l’utilisation de moyens physiques (chauffage, utilisation d’internes spécifiques) mais surtout sur l’utilisation d’additifs antimousses ou démoussants et plus particulièrement de silicones PDMS. Cependant, il n’existe pas encore d’optimisation possible de ces traitements du fait du manque d’études détaillées sur le comportement de ces systèmes complexes. L’objectif principal de ce travail a donc été de contribuer à la compréhension des mécanismes de formation, de stabilisation et de rupture des mousses non aqueuses et plus particulièrement des mousses de pétrole brut. Dans un premier temps, nous avons développé une nouvelle méthodologie expérimentale permettant de former des mousses représentatives des mousses pétrolières afin de comparer quantitativement différents systèmes moussants à base de pétroles bruts ainsi que l’efficacité de différentes familles d’additifs chimiques. Ensuite, nous avons étudié les cinétiques de cassage et développé un modèle de type sigmoïde permettant de décrire les courbes expérimentales de manière satisfaisante, et ouvrant la voie à une analyse quantitative de ces systèmes. Grâce à ce type de modélisation, il est possible de comparer l’efficacité des additifs chimiques en tant que démoussants et/ou antimousses et donc d’optimiser le choix du meilleur additif requis.Enfin ces développements permettent de proposer une première analyse de l’influence des caractéristiques physico chimiques de ces systèmes complexes sur leurs propriétés de moussage. / Crude oil foams are present in most steps of the oil industry, being one of the most complex and problematic non aqueous foams. During the crude oil exploitation, the presence of stable foams may cause major problems on surface equipment because of the depressurisation between the reservoir and the wellhead and the nucleation of the bubbles from the natural gas solubilised in the reservoir oil. These foams can fill up rapidly the half of the volume of the separators and cause serious damages due to the loss of the level control capacity, by dragging gas to the liquid line or liquid to the gas line, which leads to a reduction of the efficiency of the operation. The control of these foams is therefore a real issue. Several methods are used to control the foam based on its physical destruction (by mechanical devices, heating, special design of the unit internals...) but, by far, the most common method is the chemical destruction by adding different chemical compounds (called defoamers and antifoamers), particularly PDMS silicones. However, there is still no possible optimization of these treatments because of the lack of detailed studies on the behaviour of these complex systems. With this work we wanted to contribute to the understanding of the formation, stabilization and breaking mechanisms of this kind of non-aqueous foams. With this in mind, our first objective was the development of a new experimental methodology that allows to form crude oil foams which are representative of the oilfield foams, in order to compare the different foamy systems as well as the efficiency of different families of chemical additives. After that, we used a sigmoid model which describes in a satisfactory way the experimental curves of foam breaking. Besides, this kind of modelling allows to compare the efficiency of the different chemical additives in terms of defoaming and antifoaming effects, leading to the optimal selection of the additive in each case. Finally, these developments allow us to propose a first analysis of the influence of the physicochemical characteristics of these complex systems on their foaming properties.

In the present thesis, we propose a modification of silicone surfaces using the controlled deposition of amphiphilic block copolymers from aqueous colloidal dispersions. The surface modifiers are based on poly(dimethylsiloxane) (PDMS) as the hydrophobic part, in order to allow a good compatibility with PDMS artefacts, and poly(glycerol monomethacrylate) (PGMMA) as the hydrophilic block, since this polymer has demonstrated good biocompatibility and low cell attachment. The hydroxyl groups present on PGMMA offer the possibility of further surface functionalization. We have demonstrated the convenience of preparing well-defined amphiphilic block copolymers of PDMS and PGMMA (which we refer to as Sil-GMMA polymers) via atom transfer radical polymerization using a protection/deprotection route (i.e. the silylation of GMMA alcohols groups). Depending on the ratio between hydrophobic and hydrophilic blocks, Sil-GMMA copolymers can self-assemble into micellar and other colloidal structures. Diffusion ordered nuclear magnetic resonance experiments have shown that those micelles did not interact with albumin, suggesting a “stealth” behaviour. Once a library of Sil-GMMA polymers with various block ratio was prepared, the adsorption of Sil-GMMA colloidal dispersions in water/ethanol on PDMS surfaces by simple physisorption was studied. As expected, high PDMS content favoured Sil-GMMA adsorption on silicone surfaces. The presence of our surface modifiers on silicone surfaces was confirmed by a decrease in water contact angle and spectroscopy techniques. We have shown that the surface coatings were stable upon storage in water. Additionally, fibrinogen adsorption was decreased by Sil-GMMA adsorption while albumin adsorption appeared to increase. The preparation of surfaces repellent to fibrinogen and interacting with a “passivating” protein such as albumin is promising. At the same time, this thesis also reports preliminary investigations on the use of enzymes in order to incorporate new functionality to GMMA containing polymers. Although enzymatic activity was observed when using PGMMA instead of glycerol with two different enzymes (glycerol kinase and glycerol dehydrogenase), PGMMA conversions were always low (< 2%).

Biomimicry means literally ‘imitation of life’ and is providing sustainable solutions for challenges that are occurring in the human lives. To date, the biomimic research reports that wettability in nature, e.g. self-cleaning effect on a lotus leaf and a striking water strider’s leg, is related to the cooperation between the chemical composition and the topography of the surface. Moreover, this study is developing a textile substrate that goes one step further than biomimic, called ‘Biomimicking beyond nature’. The focus of this study is establishing a 100% polyamide-66 textile substrate that is switchable and reversible between hydrophobic and hydrophilic states under stimulation of UV. In this study the behaviour of a polyamide-66 textile substrate, coated with three individual photoresponsive materials (azobenzene, titanium dioxide and zinc oxide), was investigated, under stimulation of 24 hours UV and one-week of storage period in dark conditions. Silicone was added to enhance the hydrophobicity of a titanium dioxide coated substrate. A switchability effect was detected, but no reversibility effect could be observed. The only organic photoresponsive material, azobenzene, obtained no significant results to conclude that an alternation between hydrophobic and hydrophilic was even present after 24 hours of UV radiation. However, azobenzene obtained more promising results on a 100% polyester textile substrate. Even though, the H0 cannot be rejected for all three individual photoresponsive materials, the zinc oxide coated polyamide-66 substrate, did exhibit the strongest results in switchability and reversibility. Based on the characterization measurements, a switchability effect from a hydrophobic surface (ca. 120°) to a hydrophilic surface (0°) can be observed after 24 hours of UV radiation. Moreover, a reversibility effect was only reported on a zinc oxide coated polyamide-66 substrate. The substrate partially reversed back to its original state with ca. 50%. Fabricating intelligent substrates could enhance many challenges confiscating today’s life. For instance, the development of smarts membranes or microfluidic switches, that alternate their wettability upon light radiation, could improve the exhausting manual labour in watering the harvest good in the agricultural industry. Therefore, it is of great importance that further research will be conducted upon the photoresponsive material, zinc oxide, in order to achieve more stable results. This study can be added to the relatively small area of knowledge around switchability phenomenon on textile substrates and can even been reported as one of the first attempts on developing a textile substrate with switchable and reversible characteristics, by use of a facile and possibly industrialized method.

The goal of the diploma thesis is to verify the possibilities of obtaining the casting of the femur component of the customized knee replacement using the technology of Rapid Prototyping and investment casting. To get the wax pattern it is used the method of fabrication the silicon rubber mould. Its optimalization from the wax pattern quality, economy of production and cooling speed aspects is important parameter at repeated production of the wax patterns.

This masters project was undertaken to have a better knowledge of the female lion reproductive tract and to equip the author for future surgical studies on this organ system. The objectives of this study were to describe the arterial supply and histology of the female reproductive organs of the African lion. The reproductive organs of three embalmed cadavers and two fresh carcasses from three-year-old known aged nulliparous lionesses weighing between 120 kg and 140 kg were studied. The project was approved by the Animal Use and Care Committee and Research Committee of the University of Pretoria (protocol number V038-09). The arterial supply of the reproductive organs was studied and described in situ and after removal and histology was subsequently performed. A novel technique in Veterinary anatomy involving the maceration of a silicone cast was used in the two fresh carcasses and all five specimens were incorporated in the comparative and arterial studies. Histology was performed on organs from the three embalmed cadavers. The anatomical information obtained during this study was subsequently applied in a surgical study on sixteen lionesses using laparoscopy to perform laparoscopic ovariectomy and salpingectomy. The availability of these two laparoscopic procedures subsequently led to a wider interest to its application in population control of lions in the smaller national parks of South Africa. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Anatomy and Physiology / unrestricted

The process of color-matching any color product is a process that can be quite complicated and requires great skill from a color analyst. As the name suggests color-matching is the process in which the color of a standard is obtained from a sample through careful inspection and precision in order for the colors to match up. It is a process that can vary in length dependent of the amount of pigments used.  Foundations are a type of liquid emulsion cosmetic and consist of five main pigments; white (titanium dioxide), red, brown, yellow and black iron oxides. These five pigments can when mixed together result in hundreds of shades. One of the greatest challenges for cosmetics companies is to successfully manufacture these shades often from a benchmark, a desired shade, as well as maintaining this same shade when the batch is scaled up from lab production to factory.  Oriflame is a direct-selling cosmetics company in which the Marketing department and Color Cosmetic department work closely in order to produce new products and shades for each catalogue. Liquid foundation shades are decided by the Marketing department and given to the Color Cosmetic department to color-match.  Currently the process of color-matching is carried out through the visual assessment by the color analyst. In order to improve the efficiency and lead - time of the current method, Oriflame has drawn inspiration from other sectors dealing with color and taken the decision to color-match with the use of a spectrophotometer coupled with color-appropriate software. The method was divided into four separate processes; confirming a sample method presentation to the spectrophotometer, colorant file set-up &amp; process, color-matching process with the color-appropriate software and color match comparison. The results showed that with an adequate sized colorant file a method for color-matching with a spectrophotometer was established. The lead-time could be decreased by, as much as 66.6 % and providing strong evidence that this is a valuable tool for color analysts working at Oriflame.

Vocal fold models are valuable for studying voice production. They provide an alternative method of studying the mechanics of the voice that does not require in vivo experimentation or the use of excised human or animal tissue. In this thesis, a new method of creating vocal fold models through additive manufacturing is described. The purpose of this research was to reduce model fabrication time, to decrease the number of model failures during manufacturing, and to lay the foundation for creating models with more lifelike geometric and material properties. This research was conducted in four stages. First, a suitable silicone additive manufacturing technique using a UV-curable silicone was chosen. The technique chosen was called freeform reversible embedding (FRE) and involved embedding liquid silicone material into a gel-like medium named organogel. The UV-curable silicone's material properties were identified to confirm its utility in vocal fold model design. Second, an open-source, fused deposition modeling slicing software was selected to create g-code for the printer. Applicable software settings were tuned through qualitative printing tests to find their optimal values for use in FRE printing. Third, 3D-printed cubes were used in tensile tests to characterize the material properties of FRE-printed, silicone material. The cubes were found to be anisotropic, exhibiting different modulus values corresponding to the layer orientation of the printed material. Fourth, vocal fold models were FRE-printed in two different layer orientations and were used in phonation tests to gather data for onset pressure, vibratory frequency, amplitude, and flow rate. The printed models self-oscillated and withstood the strains induced by phonation. These tests showed that layer direction affects the phonation properties of the models, demonstrating that models with layers in the coronal plane had slightly lower frequencies and onset pressures than models with layers in the sagittal plane. The models' onset pressures were higher than what is found in human vocal folds. However, their frequencies were within a comparable range. These tests showed the effectiveness of additive manufacturing in the application of vocal fold fabrication, reducing production effort by allowing researchers to go directly from model design to fabrication in a single manufacturing step. It is anticipated that this method will be modified to incorporate printing of multiple stiffnesses of silicone to better mimic the material properties of vocal fold tissue, and that the anisotropy of 3D-printed material will be leveraged to model the anisotropy of human vocal folds. This work also has potential application areas outside of voice research.

In this thesis, a method to improve survivability is developed for fiber Bragg gratings under high velocity impact in dynamic body armor shape sensing applications by encasing the fiber in silicone. Utilizing the slipping of the fiber within the silicone channel, a proportionality relationship between the strain of the fiber to the acceleration of the impacting projectile is found and is used to obtain the rate of the back-face deformation. A hybrid model is developed to handle errors caused by the stick-slip of the fiber by fitting an inverse exponential to stuck sections found in a captured strain profile and double integrated to transform the stuck section to its equivalent slipping. Displacement errors below 10% was achieved using the hybrid model. A graphical user interface with a step-by-step walkthrough and a fiber Bragg grating interrogation system was designed for test engineers to utilize this technology. Test engineers from the Army Test Center in Aberdeen, MD were trained on this technology and successfully captured and processed shots using this technology. A method for cutting Silicon through wire-EDM machining is developed by utilizing the photoconductive properties of Silicon. Cut rates for unilluminated and illuminated Silicon was compared and a 3x faster cut was achieved on the illuminated cuts.

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