Síntese, caracterização, propriedades e aplicação dos sistemas Mg- Al, Zn-Al e Mg-Fe

The Layered Double Hydroxides has become extremely promising materials due to its range of applications, easily obtained in the laboratory and reusability after calcination, so the knowledge regarding their properties is of utmost importance. In this study were synthesized layered double hydroxides of two systems, Mg-Al and Zn-Al, and such materials were analyzed with X-ray diffraction and, from these data, we determined the volume density, planar atomic density, size crystallite, lattice parameters, interplanar spacing and interlayer space available. Such materials were also subjected to thermogravimetric analysis reasons for heating 5, 10, 20 and 25 ° C / min to determine kinetic parameters for the formation of metaphases HTD and HTB based on theoretical models Ozawa, Flynn-Wall Starink and Model Free Kinetics. In addition, the layered double hydroxides synthesized in this working ratios were calcined heating 2.5 ° C / min and 20 ° C / min, and tested for adsorption of nitrate anion in aqueous solution batch system at time intervals 5 min, 15 min, 30 min, 1h, 2h and 4h. Such calcined materials were also subjected to exposure to the atmosphere and at intervals of 1 week, 2 weeks and 1 month were analyzed by infrared spectroscopy to study the kinetics of regeneration determining structural called "memory effect"

Horticultura no baixo curso do Rio Doce, zona norte do Natal/RN: avaliação da qualidade da água por meio de ensaios ecotoxicológicos

The research is developed in areas of horticulture in the city of Natal, in the neighborhoods of Lagoa Azul, Pajuçara and Redinha, along the Doce River, border area with Extremoz city, Rio Grande do Norte State. The region of the fluvial plain of Doce River is located in an Environmental Protection Zone (ZPA-9). This is one of the ZPA which is not under the regulatory marks and there are several environmental problems caused by use and land occupation, featuring an evident disregard of environmental laws and whose protection is hindered by the lack of specific legal mechanisms. This study aims to provide an overview of the use of pesticides in the lower course of the Doce River, in Natal, Rio Grande do Norte, and to assess environmental degradation in the area through chronic toxicity tests using the microcrustaceous Ceriodaphnia dubia Richard 1894 (Cladocera, Crustacea) as test organism. Visits were made to the area in 2009 and 2010. To obtain information a diagnosis of the local situation was accomplished based on personal observation and non-participatory photographic record, with the aim of assessing the environmental characteristics, population diversity and work processes of horticulturists. During the visits four different points of the Doce River were chosen to collect water for ecotoxicological tests and survey of physico-chemical parameters (dissolved oxygen, pH, chloride, turbidity, conductivity and temperature), which were measured in the field using Multiparameter Probe (TROLL 9500). The adverse effects of pesticide use in the lower course of the Doce River is a major problem for both the environmental and human health, since many of the substances and active principles that enter in the composition of the products are synthesized molecules whose effects can only be evaluated through different studies on their actions and behavior at short, medium or long term

Caracterização geológica, geomorgológica e geotécnica de um corpo de dunas na cidade de Natal-RN

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

O laboratório de ensino de matemática temático centrado nos instrumentos de navegação: uma proposta para o IFRN de Mossoró-RN

This work presents a proposal to build a Mathematics Teaching Laboratory (MTL) whose main theme is the study, construction and use of instruments for navigation and location of mathematical content in an interdisciplinary way approach, and develop a notebook of activities focused on navigational instruments. For this it was necessary a literature review to understand the different conceptions of MTL and its pedagogical implications. The methodology used was literature research, construction and handling of instruments, and pedagogical experimentation. Lorenzato (2006) highlights the importance of an environment and suitable for a professional who can do a good job instruments. The implementation of an LEM can find some obstacles. The lack of support from other teachers or the management, the lack of a suitable place to store the materials produced, the lack of time in the workload of the teacher to prepare the lab activity, etc. Even in unfavorable or adverse conditions, according Lorenzato (2006), its implementation will benefit teachers and students. The lack of teacher training in their initial and continuing education, to use materials, and the lack of manuals with lab activities are also mentioned as factors that keep teachers from MTL. With propóposito assist the teacher of elementary or middle school in building a theme MTL prepared and we are providing a notebook of activities that provides a didactic sequence involving History and Mathematics. The book consists of four accompanied by suggestions for teachers activities, however the teacher has full autonomy to adapt the activities to the reality of your school. Among the instruments of navigation presented in this study chose to build the quadrant due to its simplicity, low cost of material and great teaching potential that this instrument has. But a theme lab is always being built and rebuilt as it is a research environment

Estudo de um sistema de frenagem eletromagnética empregando correntes parasitas

This work deals with the analytical, computational and experimental study of phenomena related to the Eddy current induction in low permeability means for embedded electromagnetic braking systems applications. The phenomena of forces generation in opposing to the variation of stationary magnetic flux produced by DC power supplies, set in motion by the application of an external propulsive force are addressed. The study is motivated by search for solving the problem of speed control of PIGs used to verifying and maintaining pipelines, and is led based on the analytical models synthesis, validated by means of computer simulations in Finite Elements environment, provided by engineering support software; and with experimental tests conducted under controlled laboratory conditions. Finally, a damping systems design methodology based on analyzes results conducted throughout the study is presented

Influência da granulometria e taxas de filtração no tratamento de água utilizando dupla filtração

The contamination of water sources of public drinking by waste originated by anthropogenic activities has brought various risks to human health. Among the consequences of such activities can highlight the bloom of microalgae and cyanobacteria, which have the potential to produce toxins dangerous to humans, and the presence of humic substances that are generated by the decomposition of natural organic matter (NOM), such as vegetation. When found in water sources for public supply, present negative aspects conferring high color, odor and taste. The double filtration technology has good efficiency in water with the presence of cyanobacteria and different quality variations. Therefore, this study aimed to evaluate the behavior of the technique of double filtration with pre-oxidation for water purifiers the lagoon of Extremoz-RN, which currently has high concentrations of cyanobacteria. The research is summarized in four phases: the first phase turned to static tests in jarteste equipment in the laboratory and subsequent phases were tested in the Pilot Plant of Double Filtration. For the second and third stage filtration rates were tested filtration rates of 120 and 180 m3 / m2 .day for ascending boulders filters and 160 and 240 m3 / m2 .day in the filters in quick sand descendants. The last phase aimed to evaluate the double filtration with pre-oxidation. The results demonstrated that the system could produce double filtration in all trials of good quality water according to the Decree nº. 2914/11 of the Ministry of Health. The use of preoxidation favored the removal of microcystin and color at the end of the tests, reaching a percentage of color removal around 60%. The analysis of variance in the data, enabled prove that the filtration rates of 180 m3 / m2.d the gravel filter and 240 m3 /m2 .d in rapid filters, were the most significant for the removal of turbidity. The ascending filter of boulder 4 with particle size finer filter layer showed the best performance and the best means of turbidity and apparent color. The rapid filter downward 1 was more efficient in removing turbidity reaching removal about 100%

Ambiente de inovação no Laboratório de Inovação Tecnológica em Saúde – LAIS/UFRN: mapeamento, interações e gerenciamento

Innovation has become an increasingly central issue of great reputation, not only in literature but also in management practices, becoming a strategic issue for managers of organizations. Allied to this, there is a high degree of competitiveness on the market, which contributes to the complexity of decision making, since managers need to maintain a continuous cycle of renewal processes and products. Thus, market pressures for new alternatives encourage innovation within organizations as a foundation for culture change in pursuit of survival and increased competitiveness, making it essential to know the factors that promote the advancement of organizational environments targeted innovation. Confirming this view, Bouchikhi and Kimberly (2001) symbolically expressed the idea with two statements: (1) companies need to innovate to survive, otherwise they die; and (2) the wide recognition of this need, as well as the difficulty to encourage and support innovation and entrepreneurship in business, has generated a mini-industry research and consulting in management focused on these topics. This study is characterized as descriptive with qualitative and quantitative methods. As for the planning of the research, it was decided to bibliographical research and the case study. The research, developed here, is meant to examine the organizational environment of a laboratory focused on technological innovation in health, which is a reference in research and technology of Rio Grande do Norte, and ensure that it presents opportunities to develop innovations. Therefore, the technologies developed by the Laboratório de Inovação Tecnológica em Saúde - LAIS/UFRN were mapped and then a questionnaire with the stakeholders of LAIS/UFRN was applied. This questionnaire is closed and Likert scale. As a result, it follows that the dimensions 1, 6, 7 and 8 are the most influential to form an innovative environment at LAIS.

Avaliação da conformidade dos blocos cerâmicos produzidos em algumas cerâmicas no Rio Grande do Norte

The final quality of the works accomplished by the building construction industry depends directly on the quality of the materials supplied and used during all their phases of execution. The federal government participation and several state programs have established conditions to stimulate and require the increment of the quality level in the building construction industry´s product chain. These programs aim at the product conformity to the technical standards. Within this context, the evaluation program of the ceramic product conformity in Rio Grande do Norte state is assessing the conformity degree to Brazilian Technical Standards of ceramic bricks and tiles made in the ceramic production area in the state. In this work, is determine the degree of conformity of the sealing ceramic bricks made by some companies in different areas of the state, such as Assú, São Gonçalo do Amarante, Apodi, Parelhas, São José do Mipibu e Macaíba. Using the technical standards as a point of reference, we attempted to reproduce in the laboratory the experimental procedures to the analysis execution, according to the specifications. It was possible to determine that none of the evaluated samples are in strict conformity with the current technical standards, what reflects the real situation of the products available on the market.

Topologia de gerador de distúrbios elétricos baseada em conversores de potência

Electrical disturbances such as voltage sags, interruptions and voltage unbalances might cause serious problems for the end-user and for the companies of generation and transmission of energy. Few years ago, those companies have been using methods and equipments of protection to avoid the disturbances’ presence or to mitigate their effects on the power system. Disturbances generators are used to analyse the behavior of electrical and electronic equipments affected by disturbances. The analysis of those failures allows the development of appropriated protection equipments. In this paper, the development of a disturbances generator based on power converters is presented. The disturbance generator developed is able to generate some symmetrical disturbances, such as: voltage sags, voltage swells and harmonic distortion. The control strategy used in the disturbance generator is based on discrete and repetitive control. The steps of the design of the control and of the filter used for reducing harmonic in the output, are detailed in the text. Are presented the obtained results on computational simulations and the obtained results on laboratory tests.

Influência do retardante de chamas nas propriedades mecânicas e flamabilidade em compósitos poliméricos de epóxi/fibra de curauá

Currently, there is a great search for materials derived from renewable sources. The vegetable fibers as reinforcement for polymer matrixes, has been used as an alternative to replace synthetic fibres, being biodegradable and of low cost. The present work aims to develop a composite material with epoxy resin reinforced with curauá fibre with the addition of alumina trihydrate (aluminum hydroxide, Al(OH)3) as a flame retardant, which was used in proportions of 10 %, 20% and 30% of the total volume of the composite. The curauá fibers have gone through a cleaning process with an alkaline bath of sodium hydroxide (NaOH ), parallelized by hand and cut carding according to the default length . They were molded composites with fibers 30cm. Composites were molded in a Lossy Mold with unidirectional fibres in the proportion of 20% of the total volume of the composite. The composites were prepared in the Chemical Processing Laboratory of the Textile Engineering Department at UFRN. To measure the performance of the material, tests for the resistance to traction and flexion were carried out. with samples that were later analyzed in the Electronic Microscopy Apparatus (SEM ). The composites showed good mechanical properties by the addition of flame retardant and in some cases, leaving the composite more vulnerable to breakage. These mechanical results were analyzed by chi-square statistical test at the 5% significance level to check for possible differences between the composite groups. Flammability testing was conducted based on the standard Underwriters Laboratory 94 and the material showed a satisfactory result taking their average burn rate (mm / min) decreasing with increasing addition of the flame retardant composite.

Avaliação da aplicabilidade de correlações matemáticas e redes neurais na predição de parâmetros de especificação do diesel

Diesel fuel is one of leading petroleum products marketed in Brazil, and has its quality monitored by specialized laboratories linked to the National Agency of Petroleum, Natural Gas and Biofuels - ANP. The main trial evaluating physicochemical properties of diesel are listed in the resolutions ANP Nº 65 of December 9th, 2011 and Nº 45 of December 20th, 2012 that determine the specification limits for each parameter and methodologies of analysis that should be adopted. However the methods used although quite consolidated, require dedicated equipment with high cost of acquisition and maintenance, as well as technical expertise for completion of these trials. Studies for development of more rapid alternative methods and lower cost have been the focus of many researchers. In this same perspective, this work conducted an assessment of the applicability of existing specialized literature on mathematical equations and artificial neural networks (ANN) for the determination of parameters of specification diesel fuel. 162 samples of diesel with a maximum sulfur content of 50, 500 and 1800 ppm, which were analyzed in a specialized laboratory using ASTM methods recommended by the ANP, with a total of 810 trials were used for this study. Experimental results atmospheric distillation (ASTM D86), and density (ASTM D4052) of diesel samples were used as basic input variables to the equations evaluated. The RNAs were applied to predict the flash point, cetane number and sulfur content (S50, S500, S1800), in which were tested network architectures feed-forward backpropagation and generalized regression varying the parameters of the matrix input in order to determine the set of variables and the best type of network for the prediction of variables of interest. The results obtained by the equations and RNAs were compared with experimental results using the nonparametric Wilcoxon test and Student's t test, at a significance level of 5%, as well as the coefficient of determination and percentage error, an error which was obtained 27, 61% for the flash point using a specific equation. The cetane number was obtained by three equations, and both showed good correlation coefficients, especially equation based on aniline point, with the lowest error of 0,816%. ANNs for predicting the flash point and the index cetane showed quite superior results to those observed with the mathematical equations, respectively, with errors of 2,55% and 0,23%. Among the samples with different sulfur contents, the RNAs were better able to predict the S1800 with error of 1,557%. Generally, networks of the type feedforward proved superior to generalized regression.

Análise de microestrutura e de características geotécnicas de misturas de resíduo de polimento de porcelanato e solo

Brazil is a country in development, rich in natural resources. In order to grow sustainably, it is necessary to Brazil to preserve its environment, which is an expressive challenge, especially to industries, such as those producing ceramic materials. This study was developed using Porcelain Tile Polishing Residue (RPP) in blends with soil to build compacted fills. This residue is a slurry generated during the polishing process of porcelain tiles and contains powdery material from the polished tile, the abrasives used during the process and cooling water. The RPP was collected from a private company located in Conde/PB and it was mixed with a sandy-clayey soil, to build the fills. Laboratorial tests were conducted with pure soil, pure RPP and blends in proportions of 5%, 10%, 15% and 20% of RPP in addition to the dry mass of pure soil. The Chemical and Physical Characterization tests performed were: specific solid weight, grain size distribution, laser analysis of grain size distribution, Atterberg limits, X ray fluorescence, X ray diffraction, scanning electron microscopy and soil compaction,. The materials and blends were also compacted and direct shear tests and plate load tests were performed. Plate load tests were conducted using a circular plate with 30 cm diameter, on specimens of pure soil and 5% blend, compacted in a metallic box inside the Soil Mechanics Laboratory of the Federal University of Rio Grande do Norte, Brazil. Both mechanical tests performed were conducted under inundated conditions, willing to reduce the influence of soil suction. An evaluation of the results of the tests performed shows that RPP is a fine material, with grain size distribution smaller than 0,015mm, composed mainly of silica and alumina, and particles in angular shape. The soil was characterized as a clayey sand, geologically known as a lateritic soil, with high percentages of alumina and iron oxide, and particles with rounded shape. Both the Soil and the blends presented low plasticity, while the residue showed a medium plasticity. Direct shear tests showed that the addition of RPP did not cause major changes into blends’ friction angle data, however, it was possible to note that, for the proportions studied, that is a tendency of obtain lower shear stresses for higher percentages of RPP in the blends. Both pure soil and 5% mixture showed a punching disruption for the Plate load test. For this same test, the allowable stress for 5% mixture was 44% higher than the pure soil, and smaller vertical settlement results for all stresses.

Análise de microestrutura e de características geotécnicas de misturas de resíduo de polimento de porcelanato e solo

Brazil is a country in development, rich in natural resources. In order to grow sustainably, it is necessary to Brazil to preserve its environment, which is an expressive challenge, especially to industries, such as those producing ceramic materials. This study was developed using Porcelain Tile Polishing Residue (RPP) in blends with soil to build compacted fills. This residue is a slurry generated during the polishing process of porcelain tiles and contains powdery material from the polished tile, the abrasives used during the process and cooling water. The RPP was collected from a private company located in Conde/PB and it was mixed with a sandy-clayey soil, to build the fills. Laboratorial tests were conducted with pure soil, pure RPP and blends in proportions of 5%, 10%, 15% and 20% of RPP in addition to the dry mass of pure soil. The Chemical and Physical Characterization tests performed were: specific solid weight, grain size distribution, laser analysis of grain size distribution, Atterberg limits, X ray fluorescence, X ray diffraction, scanning electron microscopy and soil compaction,. The materials and blends were also compacted and direct shear tests and plate load tests were performed. Plate load tests were conducted using a circular plate with 30 cm diameter, on specimens of pure soil and 5% blend, compacted in a metallic box inside the Soil Mechanics Laboratory of the Federal University of Rio Grande do Norte, Brazil. Both mechanical tests performed were conducted under inundated conditions, willing to reduce the influence of soil suction. An evaluation of the results of the tests performed shows that RPP is a fine material, with grain size distribution smaller than 0,015mm, composed mainly of silica and alumina, and particles in angular shape. The soil was characterized as a clayey sand, geologically known as a lateritic soil, with high percentages of alumina and iron oxide, and particles with rounded shape. Both the Soil and the blends presented low plasticity, while the residue showed a medium plasticity. Direct shear tests showed that the addition of RPP did not cause major changes into blends’ friction angle data, however, it was possible to note that, for the proportions studied, that is a tendency of obtain lower shear stresses for higher percentages of RPP in the blends. Both pure soil and 5% mixture showed a punching disruption for the Plate load test. For this same test, the allowable stress for 5% mixture was 44% higher than the pure soil, and smaller vertical settlement results for all stresses.

A razão embotada: ensaios de crítica literária

A obra "A razão embotada: ensaios de crítica literária", de autoria do prof. Andrey Pereira de Oliveira, do Departamento de Letras da UFRN, é composta por 14 ensaios que discorrem acerca de obras das literaturas brasileira e universal. Os textos tiveram uma primeira publicação em livros coletivos, revistas acadêmicas ou anais de congressos científicos e passaram por adaptações para reunião neste volume.

Estruturas cerâmicas a base de zircônia e alumina utilizadas na confecção de infra - estruturas para coroas e pontes fixas

The continuous advances in ceramic systems for crowns and bridges infrastructure getting researchers and manufacturers looking for a material that has good mechanical properties and aesthetic. The purpose of this study was to verify in which composition and sintering temperature the ceramic system for infrastructure composed of alumina and zirconia would have the best mechanical properties. With this objective we made in UFRN laboratories 45 test bodies in the form of rectangular bars with the following dimensions: 30mm x 8mm x 3mm, where we separated by the sintering temperature: 1200°C, 1300ºC and 1400ºC, and by comp osition: 33% Zirconia + 67% Alumina; 50% Zirconia + 50% Alumina and 25% Zirconia + 75% Alumina, these test bodies were not infiltrated with glass. Also, were made nine test bodies by a technical from a laboratory with a commercial ceramic system: in the Ceram Zircônia (Vita - Zahnfabrik) with the following dimensions: 20mm x 10mm x 0.5mm, these test bodies following all recommendations of the manufacturer and were infiltrated with glass. Were realized optical and electronic microscopy analyses, hardness testing, resistance to bending in three points, porosity and bulk density. After analysis of the results we verified that with the increasing of sintering temperature, increased the value of resistance to bending, but with the same temperature there was no significant difference between the different compositions, samples made with the commercial ceramic that were infiltrated, presented a resistance to bending six times greater than the samples sintered to 1400°C and which have not been infiltra ted. There was no significant difference between the values of apparent porosity for the samples made in UFRN laboratories, but the samples of commercial ceramic obtained 0% in porosity apparent value. In tests of Rockwell Hardness there is an increase in the value of Hardness, with the increase of sintering temperature for the samples not infiltrated. Samples infiltrated showed similar values as the samples sintered in 1400°C. There was no significant difference between the values of apparent density among samples manufactured in UFRN laboratories and samples made with a commercial ceramic