O objetivo deste trabalho é verificar como a arte e a moda, representam o cotidiano no contemporâneo, principalmente no que diz respeito à crítica ao sistema vigente, a representação do instante formador do cotidiano e da apropriação da arte pelo consumo. Por necessidade de um recorte metodológico as Artes de Muro também conhecidas como Grafites foram escolhidas como fenômeno de observação por ser uma arte pública e de fácil acesso a maioria dos indivíduos que interagem com o espaço urbano. Observa-se que embora a Arte de Muro seja em sua maioria uma crítica aos moldes impostos pelo sistema, ela acaba por ser aglutinada por ele e transformada em bens de consumo de alto valor. / The objective of this work is to see how art and fashion, represent the everyday in contemporary, especially with regard to the criticism of the current system, the representation of time trainer every day and appropriation of art by consumption. On the need for a methodological approach for the Arts also known as Wall Graffiti were chosen as a phenomenon of observation to be a public and easily accessible to most individuals who interact with the urban space art. It is observed that although the Art Wall is mostly a critique of the molds imposed by the system, it turns out to be bonded by it and transformed into consume high value goods.

Orientador: Etienne Ghislain Samain / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Artes / Made available in DSpace on 2018-08-21T11:25:50Z (GMT). No. of bitstreams: 1 Barros_ErnaRaisaLimaRodriguesde_M.pdf: 17623615 bytes, checksum: 3fe497bb6760be522d553bdb37a2d353 (MD5) Previous issue date: 2012 / Resumo: Nossa pesquisa se constitui em uma tentativa de aproximação com o universo do grafite e aborda alguns aspectos de sua linguagem enquanto prática transgressora, arte contestatória, subversiva, mas também enquanto forma de expressão e representação artística que tem a capacidade de informar, carregar idéias e também de ser apresentado como veículo de expressão lúdica e poética presente nas cidades. Propomo-nos a refletir representações e intervenções estéticas que se referem a temáticas e questionamentos singulares com os quais nos munimos para pensar o papel das imagens na contemporaneidade, e o mundo através da arte / Abstract: Our research is an attempt to approach the world of graffiti and some aspects of their language as a practice transgressive, contestatory, subversive art, but also as a form of artistic expression and representation that has the ability to inform, carrying ideas and also to be presented as a means of ludic and poetic expression present in the cities. We propose to reflect representations and aesthetic interventions that relate to issue and questions with which we equip us to think the role of images in contemporary society and the world through art / Mestrado / Multimeios / Mestre em Multimeios

This thesis contains the results of molecular dynamics simulations of molecule-surface interactions, looking particularly at fullerene molecules and carbon surfaces. Energetic impacts of fullerene molecules on graphite create defect craters. The relationship between the parameters of the impacting molecule and the parameters of the crater are examined and found to be a function of the energy and velocity of the impacting molecule. Less energetic fullerene molecules can be scattered from a graphite surface and the partitioning of energy after a scattering event is investigated. It is found that a large fraction of the kinetic energy retained after impact is translational energy, with a small fraction of rotational energy and a number of vibrational modes. At impact energies where the surface is not broken and at normal incidence, surface waves are seen to occur. These waves are used to develop a method of desorbing molecules from a graphite surface without damage to either the surface or the molecules being desorbed. A number of fullerene molecules are investigated and ways to increase the desorption yield are examined. It is found that this is a successful technique for desorbing large numbers of intact molecules from graphite. This technique could be used for desorbing intact molecules into a gas phase for mass spectrometric analysis.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第15672号 / 工博第3330号 / 新制||工||1502(附属図書館) / 28209 / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 安部 武志, 教授 垣内 隆, 教授 井上 正志 / 学位規則第4条第1項該当

An advanced concept high temperature reactor (HTR) design has been proposed - The ‘U-Battery’, which utilises a unique sealed coolant loop, and is intended to operate with minimal human oversight. In order to reduce the need for moving parts within the design, CO2 has been selected as a candidate coolant, potentially allowing a naturally circulated system. HTR fuel is held within a semi-graphitic fuel-matrix material, and this has not previously been tested within a CO2 environment. Graphite in CO2 is subject to two oxidation reactions, one thermally driven and one radiolytically. As such, the oxidation performance of fuel-matrix material has been tested within CO2 at both high temperatures and under ionising radiation within a sealed-system. Performance has been compared to that of the Gilsocarbon and NBG-18 nuclear graphite grades. Gilsocarbon is the primary graphite grade used within the currently operating AGR fleet within the UK, and as such is known to have acceptable oxidation performance under reactor conditions. NBG-18 is a modern graphite grade, and is a candidate material for use within the U-Battery. Virgin characterisation of all materials was performed, including measurements of bulk mass and volume, skeletal volumes and surface areas. High-resolution optical microscopy has also been performed and pore size distributions inferred from digital image analysis. All results were seen to agree well with literature values, and the variation between samples has been quanti- fied and found to be < 10% between samples of Gilsocarbon, and < 4% for samples of fuel-matrix and NBG-18. Thermal performance of fuel-matrix material was observed between 600 °C – 1200 °C and seen to be broadly comparable to that of the nuclear graphite grades tested. NBG-18 showed surprisingly poor performance at 600°C, with an oxidation rate of 3×10−4%/min, approximately ten times faster than Gilsocarbon in similar conditions, and three times faster than fuel-matrix material. The radiolytic oxidation performance of fuel-matrix material and NBG-18 has been observed by irradiating sealed quartz ampoules. Ampoules were pressurised with CO2 prior to irradiation, and the pressure after 30 days of irradiation was measured and seen to fall by 50%. Radiolytic oxidation, and the subsequent radiolysis of the reaction product, CO, was seen to cause significant carbonaceous deposition on the internal surfaces of the ampoule and throughout the samples. Due to the short irradiation times available in the present study, an investigation of the microporosity within irradiated samples has been carried out, using nitrogen adsorption and small-angle neutron scattering (SANS). Pore size distributions produced from SANS show the closure of microporosity within NBG-18, most likely as a result of low-temperature neutron irradiation.As a result of this work, CO2 is no longer a candidate coolant for use with the U-Battery design, due to the rapid deposition observed following irradiation.

Les conditions thermiques et le traitement du métal liquide pour la coulée centrifuge des tuyaux de canalisation permettent d'obtenir une solidification sous forme de graphite sphéroïdal sur l'ensemble de l'épaisseur. Il est parfois observé en peau des zones solidifiant selon le mode blanc qui peuvent induire des différences de réponses métallurgiques problématiques. La caractérisation de tuyaux de différents diamètres montre qu'une compétition entre la croissance de l'eutectique métastable et la germination et croissance de l'eutectique stable existe dès le tout début de la solidification. Pour préciser les conditions thermiques de cette compétition un dispositif de chute de goute sur substrat a été utilisé pour lequel la solidification rapide et dirigée se déroule avec mesure de l?évolution de la température aux premiers moments de la solidification (t<200 ms). La caractérisation des microstructures à l'état brut de coulée et après traitement thermique a montré que ce dispositif permettait de reproduire les conditions thermiques de la peau des tuyaux et de figer la structure précurseur de celle obtenue par coulée centrifuge. Un modèle physique décrivant les premiers instants de la solidification sous très fort gradient thermique d'une fonte inoculée et traitée au Mg est présenté, prenant en compte la cinétique de germination et croissance des nodules de graphite en compétition avec la solidification de l'eutectique métastable. La comparaison entre les résultats du modèle et les caractérisations microstructurales permet de préciser les scénarios de formation des microstructures en découplant l'influence du gradient thermique et de la vitesse de solidification / The thermal conditions and the treatment of the liquid metal for centrifugal casting of pipes lead to the solidification of the melt in the form of spheroidal graphite (SG) iron throughout the thickness. However it is sometimes observed zones that are solidified within the white mode (eutectic austenite / cementite) mainly in the skin of the product. These areas lead to differences which could be problematic. Further characterization of the microstructure of pipes shows that competition between the nucleation and growth of stable and metastable eutectic growth exists from the beginning of solidification. To clarify the thermal conditions of this competition an experimental device has been used. Liquid metal droplet fall on a cold substrate. Rapid directionnal solidification occurs and the temperature evolution of the lower surface of the droplet is recorded during the very first moment of solidification (< 200 ms). Characterization of droplet microstructures obtained in as-cast state and after heat treatment showed that the device is able to froze the solidified microstructure in an earlier stage of formation than in the as cast pipe. A physical model describing the first instants of the solidification under very high thermal gradient of a cast iron which is inoculated and treated with Mg is presented, taking into account the kinetics of nucleation and growth of graphite nodules in competition with the solidification of the metastable eutectic. The comparison between the calcluated results and microstructural characterizations allows to specify microstructures devlopment scenarios by decoupling the influence of the thermal gradient and solidification rate

Magister Scientiae - MSc / It is well known that a lead pencil is made of graphite, a naturally form of carbon, this is important but not very exciting. The exciting part is that graphite contains stacked layers of graphene and each and every layer is one atom thick. Scientists believed that these graphene layers could not be isolated from graphite because they were thought to be thermodynamically unstable on their own and taking them out from the parent graphite crystal will lead them to collapse and not forming a layer. The question arose, how thin one could make graphite. Two scientists from University of Manchester answered this question by peeling layers from a graphite crystal by using sticky tape and then rubbing them onto a silicon dioxide surface. They managed to isolate just one atom thick layer from graphite for the first time using a method called micromechanical cleavage or scotch tape. In this thesis chemical method also known as Hummers method has been used to fabricate graphene oxide (GO) and reduced graphene oxide. GO was synthesized through the oxidation of graphite to graphene oxide in the presence of concentrated sulphuric acid, hydrochloric acid and potassium permanganate. A strong reducing agent known as hydrazine hydrate has also been used to reduce GO to rGO by removing oxygen functional groups, but unfortunately not all oxygen functional groups have been removed, that is why the final product is named rGO. GO and rGO solutions were then deposited on silicon substrates separately. Several characterization techniques in this work have been used to investigate the optical properties, the morphology, crystallography and vibrational properties of GO and rGO.

Carbon materials play a fundamental role in the development of fusion reactors, for both the generation of electric power and the production of nuclear materials. It is possible to synthesise graphite and carbon materials from coal. Coal is available in large quantities and could be used for the production of high-purity carbon graphite. However, it contains large quantities of impurities that need to be removed prior to graphitisation/carbonisation. The impurity levels of certain elements in this graphite must be kept at very low levels. Boron, which absorbs neutrons strongly, should be below 500 ppb. Europium and gadolinium, which absorb neutrons and are activated to highly radioactive products, as is cobalt, should be as low as 50 ppb. Lithium transforms to tritium, which leads to the circulating helium becoming radioactive. Other elements, such as calcium, sodium, silicon, thorium and uranium, should not be ignored. The purpose of this study was to lower or remove completely the impurities and trace elements in coal that affect the quality of nuclear-grade graphite. The organic part of Tshikondeni coal was dissolved in a solvent, dimethylformamide (DMF), on addition of sodium hydroxide. The first stage of purification is centrifugation and filtration, which removes most of the impurities. The recovered organic material, known as ‘Refcoal’, may be converted to graphitisable coke. Some elements, significantly boron and cobalt, associate with the organic material in solution and are not sufficiently separated by centrifugation and filtration. Further purification was employed during each process step in the conversion of coal solution into graphite. Different methods of purification were employed in this study. They included chlorination, acid treatment and the ion-exchange or complexation method. Chlorine gas and hexachlorocyclohexane (benzene hexachloride) were used in the chlorination method. Acids such as hydrochloric, hydrofluoric and ascorbic were used in acid treatment. In the ion-exchange method, reagents such as methane, starch, potassium cyanide, ethylene-diaminetetraacetic acid, sodium fluoride, sodium sulphate, ice, glycerol and sodium nitrate were used. All the treated Refcoal was coked at 1 000º C. Pyrolysis was applied in other methods with the aim of volatilising elements that form volatile halides at higher temperatures. Analysis was done for elements such as calcium, cobalt, europium, gadolinium, lithium, sodium, silicon, thorium and uranium, and other elements in the periodic table. Inductively coupled plasma mass spectroscopy and inductively coupled plasma optical emission spectroscopy were used to analyse the concentrations of the trace elements in the coal (treated and untreated) and the coked Refcoal. In inductively coupled plasma mass spectroscopy, microwave digestion and fusion were applied as methods of preparation. However, the instrumentation gave different results for the same sample. The results showed that specific methods work for specific elements. The chlorination method and the acid-treatment method (especially using hydrofluoric acid and hydrochloric acid) gave better purification for most of the trace elements and other elements. Better purification was achieved with elements such as, boron, calcium, europium, gadolinium, lithium, sodium and silicon. All the treatments failed to lower uranium and thorium to the level required for nuclear-grade graphite. However, uranium has a low boron equivalent and does not pose serious problems with respect to nuclear usage. All the methods failed to remove cobalt and this remains a problem. / Dissertation (MSc (Chemistry))--University of Pretoria, 2008. / Chemistry / MSc / unrestricted

Synthetic graphite is an important industrial material, used in nuclear reactors, electrodes and many other applications. Graphitisation of coke is the solid-state transformation of the disordered carbon atoms into a well-ordered hexagonal graphite structure, requiring temperatures as high as 2 600 ºC. Catalytic graphitisation using metals or metal compounds allows the rearrangement of atoms to occur at lower temperatures. The extent of catalytic graphitisation is markedly dependent on the structural ordering of the parent coke, the catalyst concentration and the reaction conditions. Solvent extraction of coal using dimethylformamide (DMF) as a solvent yields a refined coal solution referred to as Refcoal solution. Cokes of solvent-refined Tshikondeni coal derivatives have been found to be graphitisable. The activity of acetylacetonate and hydroxyquinolinate complexes of Al, Ca, Cu, Fe and Zr for catalysing the graphitisation of Refcoal cokes at 1 600 and 2 000 ºC was investigated. The effect of residence time on the catalytic graphitisation of Refcoal cokes was investigated by heat-treating cokes for two and six hours at 1 600 °C. For iron(III)acetylacetonate, the effect of metal concentrations was studied. Samples were analysed using thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and optical microscope techniques. The results show that calcium(II)acetylacetonate catalyses the graphitisation of Refcoal cokes. The degree of graphitisation increases with an increase in the iron concentration. However, iron promotes localised graphitisation, probably in the vicinity of the catalyst particles. / Dissertation (MSc (Chemistry))--University of Pretoria, 2008. / Chemistry / unrestricted

Corrosion problems of copper waffle coolers are experienced in Platinum Group Metals (PGM’s) smelting furnaces. The copper cooler wear mechanism was studied through a post-mortem analysis of the refractory corrosion products that were removed from a PGM smelter. Post-mortem samples were characterised using Scanning Electron Microscopy (SEM), X-Ray Fluorescence Spectroscopy (XRF) and X-Ray Powder Diffraction (XRD). On visual inspection of the refractory wall it was observed that at the slag-feed interface the front refractory (mag-chrome) brick was completely corroded and only the freeze lining (frozen slag) formed a barrier between the copper cooler and the feed. At the bottom section of the slag zone the front refractory brick was still intact. Base metal sulphides and element sulphur were the major phases observed at the copper cooler-freeze lining interface while at the copper cooler-front brick interface only covellite (CuS) and element sulphur were observed. It was concluded that wear proceeded through two mechanisms: Reaction of copper with base metal sulphides which infiltrated the freeze lining and gaseous attach of copper by sulphur forming covellite. Front mag-chrome refractory bricks are replaced by graphite blocks in the latest furnace wall designs. A post-mortem graphite block was analysed with SEM, XRD and Inductively Coupled Plasma (ICP) to determine the phases associated with copper cooler corrosion. Base metal sulphides were observed at the copper cooler-graphite block (cold face) interface. Good agreement was found between the phases in the graphite block and the phases in the post-mortem sample where the refractory brick was used. Laboratory experiments were carried out to determine the effect of corrosive gas composition and copper cooler surface temperature on the corrosion rate and morphology of the corrosion products. Tests were performed on copper foils at temperatures from 80°C to 140°C. Corrosive gases included H2S, S2 and S2 with HCl. It was found that when a copper foil is exposed to sulphur the sulphides that form are covellite at 80°C, covellite and yarrowite (Cu9S8) at 110°C, yarrowite and digenite (Cu1.8S) at 140°C. Linear corrosion rate behaviour was observed between 80°C and 110°C since the sulphide scales are not passivating and they poorly adhere to the copper foil. Average corrosion rates of copper foil by sulphur vapour was 54 mm/y at 80°C and 80 mm/y at 110°C, above 112°C the corrosion rate decreased to 5 mm/y. Additions of HCl enhance the corrosion rate at temperatures above the melting point of sulphur (112°C). Chalcocite (Cu2S) forms when copper is exposed to H2S. It was concluded that the corrosion rate and the morphology of the corrosion product are functions of temperature and the corrosive gas composition. Copyright / Dissertation (MSc)--University of Pretoria, 2010. / Materials Science and Metallurgical Engineering / unrestricted