Membrana de alumina anódica: comportamento da microestrutura e estudo das propriedades ópticas após tratamento térmico

Thin commercial aluminum electrolytic and passed through reactions was obtained with anodic alumina membranes nanopores. These materials have applications in areas recognized electronic, biomedical, chemical and biological weapons, especially in obtaining nanostructures using these membranes as a substrate or template for processing nanowires, nanodots and nanofibers for applications noble. Previous studies showed that the membranes that have undergone heat treatment temperature to 1300° C underwent changes in morphology, crystal structure and optical properties. This aim, this thesis, a study of the heat treatment of porous anodic alumina membranes, in order to obtain and to characterize the behavior changes structures during the crystallization process of the membranes, at temperatures ranging between 300 and 1700° C. It was therefore necessary to mount a system formed by a tubular furnace resistive alumina tube and controlled environment, applying flux with special blend of Ag-87% and 13% N2, in which argon had the role of carrying out the oxygen nitrogen system and induce the closing of the pores during the densification of the membrane. The duration of heat treatment ranged from 60 to 15 minutes, at temperatures from 300 to 1700° C respectively. With the heat treatment occurred: a drastic reduction of porosity, grain growth and increased translucency of the membrane. For the characterization of the membranes were analyzed properties: Physical - thermogravimetric, X-ray diffraction, BET surface area; morphological - SEM, EDS through compositional and, optical absorbance, and transmittance in the UV-VIS, and FTIR. The results using the SEM showed that crystallization has occurred, densification and significant changes in membrane structure, as well as obtaining microtube, the BET analysis showed a decrease in specific surface area of the membranes has to 44.381 m2.g-1 to less than 1.8 m2.g-1 and in the analysis of transmittance and absorbance was found a value of 16.5% in the range of 800 nm, characteristic of the near infrared and FTIR have confirmed the molecular groups of the material. Thus, one can say that the membranes were mixed characteristics and properties which qualify for use in gas filtration system, as well as applications in the range of optical wavelength of the infra-red, and as a substrate of nanomaterials. This requires the continuation and deepening of additional study

Nitretação em plasma com gaiola catódica: caracterização e avaliação do desempenho da camada nitretada em facas de corte

Nowadays, in the plastic industry are used mills that accomplish the recycling of residues generated in the production of its components. These mills contain cut sheets that suffer accelerated wear, once they are submitted constantly to the tribologic efforts, decreasing its useful life. To reduce this problem, it s used noble steels or takes place superficial treatments. The ionic nitriding process presents some limitations related to the uniformity of the layer in pieces with complex geometry, committing its application in pieces as knives, head offices, engagements, etc. However, the new technique of nitriding in cathodic cage eliminates some problems, as the restrictions rings, inherent to the conventional ionic nitriding. In present work, was studied the use viabilization of steels less noble, as SAE 1020, SAE 4320 and SAE 4340, nitreded by two different techniques, to substitute the AISI 01 steels, usually used in the cut knifes fabrication, seeking to reduce the costs and at the sane time to increase the useful life of these knifes. The steel most viable was the SAE 4340, nitrided in cathodic cage, because it presented uniformity in thickness and in the hardness of the layer, besides of increased 58% in the average its useful life

Reforma a seco de metano com catalisadores Ni/MCM-41 sintetizados a partir de fontes alternativas de sílica

The production of synthesis gas has received renewed attention due to demand for renewable energies to reduce the emissions of gases responsible for enhanced greenhouse effect. This work was carried out in order to synthesize, characterize and evaluate the implementation of nickel catalysts on MCM-41 in dry reforming reactions of methane. The mesoporous molecular sieves were synthesized using as silica sources the tetraethyl orthosilicate (TEOS) and residual glass powder (PV). The sieves were impregnated with 10% nickel to obtain the metallic catalysts (Ni/MCM-41). These materials were calcined and characterized by Thermogravimetric Analysis (TG), Infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Temperature-Programmed Reduction (TPR) and N2 Adsorption/Desorption isotherms (BET/BJH). The catalytic properties of the samples were evaluated in methane dry reforming with CO2 in order to produce synthesis gas to be used in the petrochemical industry. The materials characterized showed hexagonal structure characteristic of mesoporous material MCM-41 type, being maintained after impregnation with nickel. The samples presented variations in the specific surface area, average volume and diameter of pores based on the type of interaction between the nickel and the mesoporous support. The result of the the catalytic tests showed conversions about 91% CO2, 86% CH4, yelds about 85% CO and 81% H2 to Ni/MCM-41_TEOS_C, and conversions about 87% CO2, 82% CH4, yelds about 70% CO and 59% H2 to Ni/MCM-41_PV_C. The similar performance confirms that the TEOS can be replaced by a less noble materials

Cinematografando o consumo :as narrativas e práticas culturais dos clientes de videolocadoras de Natal (RN)

The present work is an exercise of analysis of cultural practices related to movie consume by the clients of video rental stores in Natal city (Rio Grande do Norte, Brazil). With sociology of practice as support, especially that one which develops from the seminal works of Anthony Giddens and Pierre Bourdieu, we have searched, from the apprehension of the narratives build up by these actors from the movies they attend, to point the way they build exercises of reflexivity and creativity in the reception of works commonly identified as products of the so called mass culture . This path allows us, in the steps of Nestor Garcia Canclini, researcher in reception within Latin-American context, create and, somehow confirm the hypothesis that consume is also useful for thinking . In order to get to this result, we have carried out a camp research that used instruments and techniques both quantitative and qualitative. After the data analysis we came to the conclusion that consume of movies taken as commercial type and as not very noble in the environment of cultural production, also impels exercises of creativity and social reflexivity

Augusto Matraga: um hérói além do bem e do mal - uma perpectiva trágico-ntológica

The present dissertation analyses the philosophy of Friedrich Nietzsche (1844-1900) and the short story written by João Guimarães Rosa (1908-1967), A hora e vez de Augusto Matraga (1946) seeking to point out the possibility of the philosophic application of some Nietzschean ideas to enlarge the aesthetic value of the short story. It has been especially aimed at applying the concept of the noble superior being described by Nietzsche, the ubermensch, to the hero s ontological nature, Augusto Matraga. Nietzsche s postulates of the will to power, the elements suggested of the trial between Dionysus and Apollo and the ascetic ideal, will be especially relevant to this work, which intends to establish until what point the hero can be conceived as a good ascetic person, in so far as his noble ontological nature trespass the Christian morality, bringing him closer to the man who, according to Nietzsche, is beyond good and evil. Some Heideggerian concepts will also be relevant in order to reinforce the idea that the judgment created about Matraga is just an appearance that does not contemplate his essential Being, contributing to veil his real tragic-ontological valour, what implies that the aesthetic power of the short has been under valued

O princípio metafísico da poética de Aristóteles

Aristotle's definition of tragedy indicates a metaphysical project insinuated by a notion of kátharsis. The reconstruction of Aristotle's method of definition is inspired in the concepts of enérgeia and dýnamis taken from Physics, understanding cause as substance. The Doctrine of the Four Causes is the theoretical basis of the definition of tragedy, placing tragedy in the genre of imitation and distinguishing its species: language (material cause), noble and complete action (formal cause), actors (efficient cause) and kátharsis (temporarily identified with the final cause). Nevertheless, there is no final cause in the definition of tragedy. The kátharsis of passions is experienced by the spectator when he witnesses tragedy, which is the imitation of a noble action, executed by actors and not narrated. Aristotle justifies hid proposition in favor of mimesis by assuming that imitation is natural to man since infancy and the view of objects allows whoever contemplates them to identify and learn the originals. As a metaphysical principle, kátharsis is projected to beyond definition of tragedy, where it is manifested cathartically, in the spectator. Research about the spectator brings one back to the definition of tragedy, where the imitation is an imperfect copy which evokes in the spectator the presence of the originals of the imitated sentiments, thus realizing the kátharsis of these emotions. In this way kátharsis reveals itself as selfknowledge and approach of divine truth and perfections.