Síntese e caracterização de componentes nanoestruturados de células a combustível de óxidos sólidos

Perovskite-like ceramic materials present the general formula ABO3, where A is a rare earth element or an alkaline metal element, and B is a transition metal. These materials are strong candidates to assume the position of cathode in Solid Oxide Fuel Cells (SOFC), because they present thermal stability at elevated temperatures and interesting chemical and physical properties, such as superconductivity, dieletricity, magnetic resistivity, piezoelectricity, catalytic activity and electrocatalytic and optical properties. In this work the cathodes of Solid Oxide Fuel Cells with the perovskite structure of La1-xSrxMnO3 (x = 0.15, 0.22, 0.30) and the electrolyte composed of zirconia-stabilized-yttria were synthesized by the Pechini method. The obtained resins were thermal treatment at 300 ºC for 2h and the obtained precursors were characterized by thermal analysis by DTA and TG / DTG. The powder precursors were calcined at temperatures from 450 to 1350ºC and were analyzed using XRD, FTIR, laser granulometry, XRF, surface area measurement by BET and SEM methods. The pellets were sintered from the powder to the study of bulk density and thermal expansion

Desenvolvimento de componentes nanométricos para aplicação em células a combustível à base de sólidos estruturados e filmes finos

The present work aims the preparation of filmes of strontium-doped lanthanum manganite (perovskita) yttria-stabilized zirconia (LSM-SDC) films deposited on substrate of YSZ by means of spin coating technique having as principal objective their application to solid oxide fuel cells of intermediate temperature. La0,8Sr0,2MnO3 and Ce0,8Sm0,2O1,9 were obtained by modified Pechini method by use of gelatin which act as polymerization agent. The powders obtained were characterized by Xray fluorescence, X ray diffraction, electronic scanning microscopy and the superficial area by BET method. The results obtained by X-ray fluorescence showed that the route adopted for obtention of powders was effective in the obtention of the compositions with close values to the stoichiometrics. Ethyl cellulose was used as pore-forming agent and mixed with the LSM-SDC powders in weight proportions of 1:24, 2:23 and 1:9. The films were sintered at 1150 °C for 4 h and characterized by X-ray diffraction and scanning electron microscopy technique (SEM) and atomic force. The phases quantification of the precursory powders and of the obtained films was carried through Rietveld method. According with the analysis of SEM, as the content of ethyl cellulose was increased, the pore distribution in films become more uniform and the pore size reduced. The methodology used for the obtention of the films was very efficient, considering a material was obtained with characteristics that were proper to the application as electrolyte/cathode system to solid oxide fuel cells

Análise de sedimento de fundo: uma amostragem representativa do estuário Potengi/RN

The aim of this study is to quantify the presence of major and minor elements in the sediments of estuary Potengi. Four georeferenced sampling points were used in the study, at which sediment samples were collected in the channel of the river and on the right and left banks. In addition, dissolved oxygen, salinity and water conductivity were taken in situ at the time of sample collection. The percentage of organic matter, determined by gravimetry, and granulometric analysis of the sediment samples were conducted in the laboratory. To quantify the major and minor elements a prior test to open the sample was conducted with standard NIST 1646ª estuarine sediment to choose the best methodology to be adopted. The sediment samples were dissolved in microwaves with nitric acid and chloridric acid, according to methodology proposed by US EPA 3051ª. Quantitative analyses of the elements Al, Fe, Cd, Cr, Cu, Mn, Ni, Pb and Zn were conducted by inductively coupled plasma optical emission spectrometry (ICPOES). The results showed that the partial concentrations of the elements analyzed are below average worldwide shale levels, the standard described by Turekian and Wedepohl (1961)

Determinação de parâmetros (sólidos solúveis, pH e acidez titulável) em ameixas intactas usando espectroscopia no infravermelho próximo e seleção de comprimento de onda

The aim of this study was to evaluate the potential of near-infrared reflectance spectroscopy (NIRS) as a rapid and non-destructive method to determine the soluble solid content (SSC), pH and titratable acidity of intact plums. Samples of plum with a total solids content ranging from 5.7 to 15%, pH from 2.72 to 3.84 and titratable acidity from 0.88 a 3.6% were collected from supermarkets in Natal-Brazil, and NIR spectra were acquired in the 714 2500 nm range. A comparison of several multivariate calibration techniques with respect to several pre-processing data and variable selection algorithms, such as interval Partial Least Squares (iPLS), genetic algorithm (GA), successive projections algorithm (SPA) and ordered predictors selection (OPS), was performed. Validation models for SSC, pH and titratable acidity had a coefficient of correlation (R) of 0.95 0.90 and 0.80, as well as a root mean square error of prediction (RMSEP) of 0.45ºBrix, 0.07 and 0.40%, respectively. From these results, it can be concluded that NIR spectroscopy can be used as a non-destructive alternative for measuring the SSC, pH and titratable acidity in plums

Caracterização química e toxicológica da água produzida descartada em plataformas de óleo e gás na costa brasileira e seu comportamento dispersivo no mar

The production of oil and gas is usually accompanied by the production of water, also known as produced water. Studies were conducted in platforms that discharge produced water in the Atlantic Ocean due to oil and gas production by Petrobras from 1996 to 2006 in the following basins: Santos (Brazilian south region), Campos (Brazilian southeast region) and Ceara (Brazilian northeast region). This study encompasses chemical composition, toxicological effects, discharge volumes, and produced water behavior after releasing in the ocean, including dispersion plumes modeling and monitoring data of the marine environment. The concentration medians for a sampling of 50 samples were: ammonia (70 mg L-1), boron (1.3 mg L1), iron (7.4 mg L-1), BTEX (4.6 mg L-1), PAH (0.53 mg L-1), TPH (28 mg L-1); phenols (1.3 mg L-1) and radioisotopes (0.15 Bq L-1 for 226Ra and 0.09 Bq L-1 for 228Ra). The concentrations of the organic and inorganic parameters observed for the Brazilian platforms were similar to the international reference data for the produced water in the North Sea and in other regions of the world. It was found significant differences in concentrations of the following parameters: BTEX (p<0.0001), phenols (p=0.0212), boron (p<0.0001), iron (p<0.0001) and toxicological response in sea urchin Lytechinus variegatus (p<0.0001) when considering two distinguished groups, platforms from southeast and northeast Region (PCR-1). Significant differences were not observed among the other parameters. In platforms with large gas production, the monoaromatic concentrations (BTEX from 15.8 to 21.6 mg L-1) and phenols (from 2 to 83 mg L-1) were higher than in oil plataforms (median concentrations of BTEX were 4.6 mg L-1 for n=53, and of phenols were 1.3 mg L-1 for n=46). It was also conducted a study about the influence of dispersion plumes of produced water in the vicinity of six platforms of oil and gas production (P-26, PPG-1, PCR-1, P-32, SS-06), and in a hypothetical critical scenario using the chemical characteristics of each effluent. Through this study, using CORMIX and CHEMMAP models for dispersion plumes simulation of the produced water discharges, it was possible to obtain the dilution dimension in the ocean after those discharges. The dispersion plumes of the produced water modelling in field vicinity showed dilutions of 700 to 900 times for the first 30-40 meters from the platform PCR-1 discharge point; 100 times for the platform P-32, with 30 meters of distance; 150 times for the platform P-26, with 40 meters of distance; 100 times for the platform PPG-1, with 130 meters of distance; 280 to 350 times for the platform SS-06, with 130 meters of distance, 100 times for the hypothetical critical scenario, with the 130 meters of distance. The dilutions continue in the far field, and with the results of the simulations, it was possible to verify that all the parameters presented concentrations bellow the maximum values established by Brazilian legislation for seawater (CONAMA 357/05 - Class 1), before the 500 meters distance of the discharge point. These results were in agreement with the field measurements. Although, in general results for the Brazilian produced water presented toxicological effects for marine organisms, it was verified that dilutions of 100 times were sufficient for not causing toxicological responses. Field monitoring data of the seawater around the Pargo, Pampo and PCR-1 platforms did not demonstrate toxicity in the seawater close to these platforms. The results of environmental monitoring in seawater and sediments proved that alterations were not detected for environmental quality in areas under direct influence of the oil production activities in the Campos and Ceara Basin, as according to results obtained in the dispersion plume modelling for the produced water discharge

Caracterização química e toxicológica da água produzida descartada em plataformas de óleo e gás na costa brasileira e seu comportamento dispersivo no mar

The production of oil and gas is usually accompanied by the production of water, also known as produced water. Studies were conducted in platforms that discharge produced water in the Atlantic Ocean due to oil and gas production by Petrobras from 1996 to 2006 in the following basins: Santos (Brazilian south region), Campos (Brazilian southeast region) and Ceara (Brazilian northeast region). This study encompasses chemical composition, toxicological effects, discharge volumes, and produced water behavior after releasing in the ocean, including dispersion plumes modeling and monitoring data of the marine environment. The concentration medians for a sampling of 50 samples were: ammonia (70 mg L-1), boron (1.3 mg L1), iron (7.4 mg L-1), BTEX (4.6 mg L-1), PAH (0.53 mg L-1), TPH (28 mg L-1); phenols (1.3 mg L-1) and radioisotopes (0.15 Bq L-1 for 226Ra and 0.09 Bq L-1 for 228Ra). The concentrations of the organic and inorganic parameters observed for the Brazilian platforms were similar to the international reference data for the produced water in the North Sea and in other regions of the world. It was found significant differences in concentrations of the following parameters: BTEX (p<0.0001), phenols (p=0.0212), boron (p<0.0001), iron (p<0.0001) and toxicological response in sea urchin Lytechinus variegatus (p<0.0001) when considering two distinguished groups, platforms from southeast and northeast Region (PCR-1). Significant differences were not observed among the other parameters. In platforms with large gas production, the monoaromatic concentrations (BTEX from 15.8 to 21.6 mg L-1) and phenols (from 2 to 83 mg L-1) were higher than in oil plataforms (median concentrations of BTEX were 4.6 mg L-1 for n=53, and of phenols were 1.3 mg L-1 for n=46). It was also conducted a study about the influence of dispersion plumes of produced water in the vicinity of six platforms of oil and gas production (P-26, PPG-1, PCR-1, P-32, SS-06), and in a hypothetical critical scenario using the chemical characteristics of each effluent. Through this study, using CORMIX and CHEMMAP models for dispersion plumes simulation of the produced water discharges, it was possible to obtain the dilution dimension in the ocean after those discharges. The dispersion plumes of the produced water modelling in field vicinity showed dilutions of 700 to 900 times for the first 30-40 meters from the platform PCR-1 discharge point; 100 times for the platform P-32, with 30 meters of distance; 150 times for the platform P-26, with 40 meters of distance; 100 times for the platform PPG-1, with 130 meters of distance; 280 to 350 times for the platform SS-06, with 130 meters of distance, 100 times for the hypothetical critical scenario, with the 130 meters of distance. The dilutions continue in the far field, and with the results of the simulations, it was possible to verify that all the parameters presented concentrations bellow the maximum values established by Brazilian legislation for seawater (CONAMA 357/05 - Class 1), before the 500 meters distance of the discharge point. These results were in agreement with the field measurements. Although, in general results for the Brazilian produced water presented toxicological effects for marine organisms, it was verified that dilutions of 100 times were sufficient for not causing toxicological responses. Field monitoring data of the seawater around the Pargo, Pampo and PCR-1 platforms did not demonstrate toxicity in the seawater close to these platforms. The results of environmental monitoring in seawater and sediments proved that alterations were not detected for environmental quality in areas under direct influence of the oil production activities in the Campos and Ceara Basin, as according to results obtained in the dispersion plume modelling for the produced water discharge

Trabalhadores por conta própria: O trabalho dos vendedores ambulantes da passarela do Natal shopping e do Via Direta

This study aid to understand the work conditions of street vendors located on the sidewalks of two malls in Brazil Northeast Natal / RN - Both malls Natal Shopping and Via Direta, to analyze their inclusion in the informal economy and to study the supposed autonomy provided by work as self-employment in its both aspects economic and social analyzing the importance on the condition of "masters of their own business" has for the street vendors, as an alternative to not submission to the figure of the boss, that represents the exploitation of one class over another. The theoretical and methodological aspects that support this study was aimed in discussion on the restructuring of production, considering its effects on the world of work, pointing to unemployment as one of the potencies element of excluded processes that exciting workers to engage in the informal market. Informality is presented as a survival strategy and as integrating part of the reproduction of capital. This research was conducted under a critical perspective, whish has been utilized quantitative and qualitative analyses. The results of this study format questions that provided during the research process the socio-economic characterization of workers, main cause of this study, and how street vendors expres their status of workers as self-employed for their work, and the perception that they have on their form of inclusion in the informal market.

Extensões ao Projeto LVWNet: mobilidade, interação com equipamentos reais, comunicação direta, e registro dinâmico de nós

Due to the constantly increasing use of wireless networks in domestic, business and industrial environments, new challenges have emerged. The prototyping of new protocols in these environments is typically restricted to simulation environments, where there is the need of double implementation, one in the simulation environment where an initial proof of concept is performed and the other one in a real environment. Also, if real environments are used, it is not trivial to create a testbed for high density wireless networks given the need to use various real equipment as well as attenuators and power reducers to try to reduce the physical space required to create these laboratories. In this context, LVWNet (Linux Virtual Wireless Network) project was originally designed to create completely virtual testbeds for IEEE 802.11 networks on the Linux operating system. This paper aims to extend the current project LVWNet, adding to it the features like the ability to interact with real wireless hardware, provides a initial mobility ability using the positioning of the nodes in a space coordinates environment based on meters, with loss calculations due to attenuation in free space, enables some scalability increase by creating an own protocol that allows the communication between nodes without an intermediate host and dynamic registration of nodes, allowing new nodes to be inserted into in already in operation network

O Turismo como um tema de pesquisa: um diálogo epistemológico a partir das produções dos programas de pós-graduação stricto sensu da Universidade Federal do Rio Grande do Norte, no período de 2007 a 2011

The study consists in an analysis of researches with tourism issues, in Master s and Doctoral level, investigating their epistemological trends, regarding the type of study that is being produced and the methods used. It is characterized as exploratory, documental and bibliographical, having undertaken a cross-sectional study which covers the period from 2007 to 2011. It analyzes the context of academically production in tourism, the nature of these researches, the methodological aspects adopted in these theses and dissertations, the philosophical inclinations and the coherence and contribution of the same. This research uses, the Digital Library of Theses and Dissertations (BDTD) and the secretariats of the Academic Centers of the Federal University of Rio Grande do Norte (UFRN) as means to collect data. It employs the technique of sampling by judgment and undertakes the research in various Academic Centers in UFRN, using the method of content analysis. It shows that, from the 643 studies analyzed, 43 of them have themes related to tourism, which characterized this study sample. This study realizes that PPGA is the largest producer of researches on tourism issues, ahead of PPGTur, which ranks the third position, in this aspect. Also realizes that all surveys analyzed are crosssectional and the theme further investigated, with 21% of the sample, is related to the marketing aspects of tourism, with the theme Directors of Hotels and Restaurants (DHR) . This research demonstrates that all sample surveys make use of interviews, and these are, mostly, structured. Also realizes that most of these studies, with 21% of the sample, employ the method of content analysis. The references in Portuguese are surveyed about five times more than the ones in other languages. It estimates that more than half of the sample is characterized as positivist, associated with aspects of functionalism. A minority of 21% of these researches seeks to identify and recommend solutions to the tourism issues, or even represent part of them. This research concludes that the studies in tourism are mostly unifocal, being driven by issues related to the touristic trade. PPGTur produces a number still unrepresentative of studies. The theses and dissertations of the sample are limited and/or unable to analyze the changes of the phenomenon caused by the time. The studies from the sample present criteria and make use of other methods and techniques to associate with the interviews and content analysis to obtain more solid and reliable data and results. They use a low number of references in languages other than Portuguese. Most of these studies, characterized as positivist-functionalist, investigate the functioning, planning, coordination and expectations in organizations, leaving aside other issues, also relevant for tourism. The number of studies aimed at identifying solutions to the problems of tourism, or that even represents part of them, is not expressive

Panorama dos resíduos sólidos urbanos nos municípios de pequeno porte do Brasil

The panorama of Urban Solid Waste (USW) in Brazil, in general lacks information, given the immensity of the country. However, it is from available data that the public executives should define the USW management. To contribute to the choice of a model for the management of USW in small municipalities, this study reviews the related literature, showing an overview of the final disposal of USW in small municipalities. Several data and researches are discussed, concluding that the available data, despite being provided by the public managers, who often attenuate the problem, should be considered for the proposition of policies to encourage the waste treatment

A incorporação de preceitos ambientais no sistema de gestão de resíduos sólidos do município de João Câmara - RN Brasil

The reality points to the global environmental sustainability as the only viable option for addressing the crisis at hand. The move towards sustainability calls for the generation / evaluation systems in their direction, through the incorporation of environmental requirements and in line with the National Policy on Solid Waste. Therefore, the proposed research supports the importance of social and environmental vision, complementing the technical view, the system for management of solid waste from East London, which is a municipality that has a system whose inadequacies are configured in environmental risk and health. Therefore, by observing, applying the model of sustainability indicators and content analysis of interviews, this research proposes to investigate the principles of sustainability and social participation are presented and what is the perception of risk about the inadequacies in the system. The results confirmed the hypotheses of the study and draw a picture of worrying data, such as very unfavorable indicators of sustainability, lack of channels of participation, uncommitted investments with the management system, devaluation of the collector of waste and differing perceptions about the risk by making actors act in isolation. This worrying situation is eased by the appearance of a series of elements are configured as opportunities for the integration of environmental principles in the system. And despite the inability of managers to participate in the research system, yet it behaves as an opportunity to implement public policies in the area of solid waste such as: the preparation of the municipal waste, the institutionalization of selective collection and organization of cooperative with the support of companies present in the city and educational institutions as the Federal Institute. The research is an opportunity for the implementation of policies in the area of solid waste and will collaborate with the building instruments for the quality of life of residents, for the socioeconomic conditions of collectors and the move towards a sustainable society

Hábito alimentar e percepção ambiental : um estudo de caso com estudantes do Ensino Médio em Natal-RN

This study has as objective to examine the level of perception of high school students from two private schools in Natal-RN about the existence of a direct link between alimentary habit and its effects on environmental. The research was lead with 433 students, who had their school alimentary habits investigated according to the 24-hour recall method and presents the results of data collection from their opinions on participating in the generation of industrialized solid residues and their yearnings about the improvements of the standard of the food offered in the school. The students show a high rate of grading age for level at school, traditional family structure, riding, predominantly, by car or by bus in the house-school-house way, have generally all three important meals at home, feed frequently at their school, getting it from their won school, which included, mainly, soft drinks and fried or grilled appetizers; show a good knowledge about selective collectors, however with a high variation in their correct use. They show significant approval in the existence of a connection between their alimentary habits and debased effects about environmental and consider their food compounds at school could improve the offering of health/natural food, slowing industrialized foods, which are highly used, sometimes. The study on the students knowledge and concern level with regard to the interface alimentary habit-environmental impact allowed delimitating some of the mainly involved components in the alimentary choices of the same students in the school environment, what might help to develop a set of proposals that stimulates the formation of a responsible consumption standard among teenagers and the need of a consideration about the consequences of their choices

Gestão dos resíduos sólidos no Brasil e seus rebatimentos em Natal, Brasil

O artigo apresenta a gestão dos resíduos sólidos no Brasil e seus rebatimentos na cidade de Natal/RN, verificando seus aspectos ambientais, econômicos e sociais. O fracasso da coleta seletiva revelado nos baixos índices de recuperação dos materiais; a baixa relevância da inclusão socioeconômica dos catadores que participam do programa assistencialista oficial; a inexistência de estratégias oficiais para que se minimize a quantidade de resíduos que se gera cada dia e o aumento exagerado dos gastos públicos, sobretudo com o tratamento dos resíduos no aterro sanitário, demonstram que a gestão de resíduos em Natal, conforme parâmentros da Política Nacional de Residuos Sólidos, objetiva o controle destes na cidade e a consolida- ção do tratamento finalista através do envio da quase totalidade dos resíduos coletados ao aterro sanitário

Similitudes na gestão dos resíduos sólidos urbanos em países centrais e periféricos

A emergência na necessidade de se manejar os resíduos sólidos urbanos leva as administrações públicas em países centrais e periféricos a utilizarem modelos de gestão de resíduos bastante similares. A gestão dos resíduos nos países centrais é caracterizada pela eficiência na execução dos serviços (limpeza, coleta, transporte e destino final), uso de aparatos tecnológicos na execução de ditos serviços e forte tradição na separação dos materiais recicláveis a ser destinados para a reciclagem. Nos países periféricos, a gestão tradicional (coletar e descartar resíduos em lixões à céu aberto) vem sendo substituída pela gestão moderna, sobressaindo-se o controle dos resíduos em detrimento das estratégias de prevenção. Também, destaca-se a presença de trabalhadores informais que coletam e separam materiais, destinando-os à reciclagem. A partir do levantamento à referência bibliográfica especializada e na consulta a documentos oficiais e produzidos por entidades diversas, o presente artigo analisa as similitudes na gestão dos resíduos sólidos em países centrais e periféricos. A busca pela modernização nos serviços dos resíduos sem levar em conta as recomendações de documentos como a Agenda 21 caracteriza a gestão dos resíduos em países centrais e periféricos pelo ambientalismo econômico, no qual as ações de controle dos resíduos são justificadas pelos aspectos ambientais e sociais dessa gestão

Grafico misto de controle da media com amostragem em dois estagios

This paper proposes a new control chart to monitor a process mean employing a combined npx-X control chart. Basically the procedure consists of splitting the sample of size n into two sub-samples n1 and n2 determined by an optimization search. The sampling occur in two-stages. In the first stage the units of the sub-sample n1 are evaluated by attributes and plotted in npx control chart. If this chart signs then units of second sub-sample are measured and the monitored statistic plotted in X control chart (second stage). If both control charts sign then the process is stopped for adjustment. The possibility of non-inspection in all n items may promote a reduction not only in the cost but also the time spent to examine the sampled items. Performances of the current proposal, individual X and npx control charts are compared. In this study the proposed procedure presents many competitive options for the X control chart for a sample size n and a shift from the target mean. The average time to sign (ATS) of the current proposal lower than the values calculated from an individual X control chart points out that the combined control chart is an efficient tool in monitoring process mean.