RCAAP Repository

Macrozooplâncton da Zona Econômica Exclusiva do Nordeste do Brasil (segunda expedição oceanográfica - REVIZEE/NE II) com ênfase em Copepoda (Crustacea)

Objetivando-se caracterizar a densidade, abundância relativa, freqüência de ocorrência, diversidade específica e associação de espécies do macrozooplâncton oceânico da "Zona Econômica Exclusiva" foi realizado o presente estudo. A região prospectada encontra-se localizada entre os paralelos 7º28'56"S - 34º32'45"W, referente a segunda expedição oceanográfica do Programa REVIZEE/NE, realizada pelo Noc. Antares da DHN/Marinha do Brasil. As amostras foram coletadas com rede de plâncton tipo bongo com malha de 300 e 500µm, no período de 31/01 a 07/02/97 em 21 estações, totalizando 42 amostras. Foram identificados 78 taxa. A densidade total dos organismos (exceto Copepoda) variou de 2,31 a 6,06 org.m-3 (estações 55 e 56) e, para os Copepoda de 0,99 a 4,75 org.m-3 (estações 48 e 57). Em termos de freqüência de ocorrência Crustacea e Chaetognatha foram muito freqüentes; Cnidaria e Teleostei (ovos e larvas) freqüentes; Mollusca, Annelida e Chordata pouco freqüentes e Protozoa raros. A diversidade específica variou de 0,648 a 4,037 ind.bits-1. A equitabilidade variou de 0,279 a 1,0. Os baixos valores de diversidade e equitabilidade ocorreram devido à dominância de Undinula vulgaris (Dana, 1849) e Calanopia americana F. Dahl, 1894. A análise cofenética revelou um r < 0,8, demonstrando não haver grupos diferentes de Copepoda na região. A espécie de Copepoda dominante foi Undinula vulgaris, ocorrendo em todas as estações independente da malha coletora. O holoplâncton foi mais representativo, e o meroplâncton esteve representado por larvas de Decapoda e Teleostei (ovos e larvas).

Year

2004

Creators

Cavalcanti,Eliane Aparecida Holanda Larrazábal,Maria Eduarda Lacerda de

Nesting biology of Centris (Hemisiella) tarsata Smith (Hymenoptera, Apidae, Centridini)

Nests of Centris tarsata Smith, 1874 were obtained from trap-nests in areas of dry semi-deciduous forest (Baixa Grande) and caatinga (Ipirá), in the State of Bahia. Nesting occurred in bamboo canes and in tubes of black cardboard with 5.8 cm (= small tube) and 10.5 cm (= large tube) in length and 0.6 and 0.8 cm in diameter, respectively. In both areas C. tarsata nested during the wet season producing four generations in Baixa Grande and three generations in Ipirá. The immatures of one generation underwent diapause at both sites. The bees constructed their nests with a mixture of sand and oil. In general, the cells were elongated and arranged in linear series with its opening pointing towards the nest entrance. Completed nests had two to three cells in small tubes, one to seven cells in large tubes, and two to 13 cells in bamboo canes. The nest plug resembled an uncompleted cell and was externally covered with oil. The cells were provisioned with pollen, oil, and nectar. Nests were parasitized by Mesocheira bicolor (Fabricius, 1804) (Hymenoptera: Apidae) and other not identify bee species.

Year

2004

Creators

Aguiar,Cândida M. L. Garófalo,Carlos A.

Observações da dieta de Artibeus lituratus (Olfers) (Chiroptera, Phyllostomidae) em duas áreas do sul do Brasil

Este estudo foi realizado no Parque Nacional de Superagüi (PNS) e na Reserva Particular do Patrimônio Natural de Volta Velha (RPPN), ambas áreas de Mata Atlântica, nos Estados do Paraná e Santa Catarina, no sul do Brasil. Morcegos foram capturados em redes de neblina e amostras fecais foram coletadas para análise da dieta. As sementes encontradas em cada amostra foram identificadas em laboratório por meio de lupa. Cento e trinta e sete exemplares de Artibeus lituratus (Olfers, 1818) foram capturados (n = 47 no PNS, n = 90 na RPPN), e 25 e 32 amostras fecais foram coletadas para cada área, respectivamente. A dieta frugívora de A. lituratus computou de 81 a 88% do total dos itens alimentares, mostrando a importância dos frutos para esta espécie.

Year

2004

Creators

Passos,Fernando C. Graciolli,Gustavo

Diversidade e análise faunística de Sphingidae (Lepidoptera) em área de brejo e caatinga no Estado da Paraíba, Brasil

As comunidades de Sphingidae da área de brejo e área de caatinga foram estudadas com armadilhas luminosas, durante 12 meses (março/2000 a fevereiro/2001), com o objetivo de conhecer a diversidade e estabelecer alguns parâmetros para o monitoramento dessas áreas. Dezenove espécies foram coletadas, sendo 15 na área de brejo e 14 na área de caatinga. Dez espécies foram comuns às áreas, 15 foram coletadas apenas no brejo e quatro na caatinga. Callionima grisescens elegans (Gehlen, 1935) foi a espécie mais abundante nas duas áreas. A distribuição da abundância de espécies no brejo segue o modelo log normal truncado. Na caatinga o padrão de distribuição de abundância de espécies não foi discriminado pelo teste chi2, embora evidências indiretas indicam uma tendência para o modelo série log. Os parâmetros estruturais das assembléias foram estimados a partir de índices de diversidade. No brejo, enquanto a equitatividade foi maior, os índices de Shannon e Brillouin superam àqueles da caatinga. Nessa localidade, os índices de Simpson e Berger-Parker são muito maior devido a uma maior dominância. A flutuação populacional para ambas as assembléias, mostraram que suas populações são afetadas pela distribuição de chuvas durante o ano, ou mais precisamente, pelo período de reposição de água no solo, como demonstrado pelo balanço hídrico.

Year

2004

Creators

Gusmão,Maria Avany B. Creão-Duarte,Antonio José

Estimativa do tamanho de duas espécies de ciclídeos (Osteichthyes, Perciformes) predados por Lontra longicaudis (Olfers) (Carnivora, Mustelidae), através de análise das escamas

O presente estudo foi realizado no Vale do Taquari, região central do Estado do Rio Grande do Sul, sul do Brasil. Entre dezembro de 2001 e dezembro de 2002 foi realizado um estudo sobre a predação de Cichlidae por Lontra longicaudis (Olfers, 1818) através de análise das escamas encontradas nas fezes de lontra. Foi identificada a predação sobre Gimnogeophagus labiatus (Hensel, 1870) e Crenicichla punctata Hensel, 1870, e a ocorrência destas espécies de peixe na dieta é mais elevada do que sua disponibilidade relativa no ambiente. Foi encontrada uma correlação positiva entre o tamanho do peixe e das escamas, permitindo a construção de uma curva de regressão para estimar o tamanho dos peixes predados baseado no tamanho das escamas encontradas nas fezes de lontra. Neste estudo, os ciclídeos mais frequentemente predados variaram no comprimento entre 100 e 150 mm e no peso entre 22 e 37 g.

Year

2004

Creators

Kasper,Carlos Benhur Salvi,Juliana Grillo,Hamilton César Zanardi

A review of the weevil fauna (Coleoptera, Curculionoidea) of Araucaria angustifolia (Bert.) O. Kuntze (Araucariaceae) in South Brazil

The beetle superfamily Curculionoidea includes 43 species associated with Araucaria angustifolia trees in South Brazil. These weevil species belong to the families Nemonychidae (Brarus Kuschel, 1997, Rhynchitoplesius Voss, 1952), Brentidae (Taphroderes Schönherr, 1826) and Curculionidae, the latter including the subfamilies Curculioninae (Heilipodus Kuschel, 1955, Spermologus Schönherr, 1843), Cossoninae (Araucarius Kuschel, 1966, Eurycorynophorus Voss, 1964), Scolytinae (Ambrosiodmus Hopkins, 1915, Araptus Eichhoff, 1871, Cnesinus LeConte, 1868, Corthylus Erichson, 1836, Cryptocarenus Eggers, 1936, Hypothenemus Westwood, 1834, Monarthrum Kirsch, 1866, Pagiocerus Eichhoff, 1868, Phloeotribus Latreille, 1896, Pityophthorus Eichhoff, 1864, Xylechinosomus Schedl, 1963, Xyleborus Eichhoff, 1864, Xyleborinus Reitter, 1913) and Platypodinae (Cenocephalus Chapuis, 1865, Platypus Herbst, 1893, Tesserocerus Saunders, 1836). A checklist of all species including remarks on their life histories and taxonomic notes are presented. In addition, a key for the identification of adult Curculionoidea associated with Araucaria angustifolia to genus or species level is provided.

Year

2004

Creators

Mecke,Roland Galileo,Maria Helena M.

Brasilochondria riograndensis gen. nov., sp. nov. (Copepoda, Chondracanthidae) a parasite of flounders of Rio Grande do Sul State, Brazil

Brasilochondria riograndensis gen. nov., sp. nov. (Copepoda, Chondracanthidae) a parasite of the flounder, Paralichthys orbignyanus (Valenciennes, 1839), is described. The new genus has a spherical head a post-mandibular "neck" and two pairs of modified biramous legs. In these respects, it resembles Argentinochondria patagonensis Etchegoin, Timi &amp; Sardella, 2003. In the Argentine genus, however, the bulbous head has a medial constriction and the posterior of the female lacks the lateral extensions that are present in the new genus. Pseudolernentoma brasiliensis Luque &amp; Alves, 2003, also resembles the new genus but it lacks the lateral extensions of the trunk and the latter is cylindrical rather than flat. The second leg of the new genus is small and the endopod is shorter than the exopod. The other two genera have large second legs with subequal rami.

Year

2004

Creators

Thatcher,Vernon E. Pereira Júnior,Joaber

Decomposição da variação da pobreza em efeito crescimento e desigualdade

This article proposes to estimate the growth elasticity of poverty and inequality of poverty and decompose the change in the poverty of its main determinants: growth and poverty. So, we followed a similar methodology in Besley, Burgess and Volart (2005). We used the information from PNAD's for the years 1995 to 2007, except 2000, for measures of poverty P0, P1 and P2, with data in the panel for 27 units of the federation in Brazil. Specification tests point to an estimation with elasticities varying between states. The results indicate a large inter-state disparities in growth elasticities of poverty, where the units of the federation are also the less wealthy who have lower growth elasticity of poverty. The decomposition of poverty variation indicates only the units of the federation AP, RJ, RR, RS and SP showed elasticity effect of growth above the national average, together with further growth of national income on average (for P0). Furthermore, BA, CE, MA, MS, MT, PB, PI, RN, SE and TO show elasticity growth below the national average in conjunction with lower growth in income on the national average (for P0). Very similar result is found for P1 and P2.

Year

2011

Creators

Salvato, Márcio Antônio Matias, Jonathan de Souza Barreto, Flávio Ataliba Flexa Daltro Manso, Carlos Alberto

Análise da qualidade do crescimento econômico nos estados brasileiros de 1995 a 2008: quão elásticos são os indicadores de pobreza com relação ao crescimento?

This article proposes to estimate the growth elasticity of poverty and inequality of poverty and decompose the change in the poverty of its main determinants: growth and poverty. So, we followed a similar methodology in Besley, Burgess and Volart (2005). We used the information from PNAD's for the years 1995 to 2007, except 2000, for measures of poverty FGT(0), FGT(1) and FGT(2), with data in the panel for 27 units of the federation in Brazil. Specification tests point to an estimation with elasticities varying between states. The results indicate a large inter-state disparities in growth elasticities of poverty, where the units of the federation are also the less wealthy who have lower growth elasticity of poverty. The decomposition of poverty variation indicates only the units of the federation AP, RJ, RR, RS and SP showed elasticity effect of growth above the national average, together with further growth of national income on average (for FGT(0)). Furthermore, BA, CE, MA, MS, MT, PB, PI, RN, SE and TO show elasticity growth below the national average in conjunction with lower growth in income on the national average (for FGT(0)). Very similar result is found for FGT(1) and FGT(2).

Year

2011

Creators

Matias, Jonathan de Souza Salvato, Márcio Antônio Barreto, Flávio Ataliba Flexa Daltro

The forward- and the equity-premium puzzles: two symptoms of the same illness?

Using information on US domestic financial data only, we build a stochastic discount factor—SDF— and check whether it accounts for foreign markets stylized facts that escape consumption based models. By interpreting our SDF as the projection of a pricing kernel from a fully specified model in the space of returns, our results indicate that a model that accounts for the behavior of domestic assets goes a long way toward accounting for the behavior of foreign assets prices. We address predictability issues associated with the forward premium puzzle by: i) using instruments that are known to forecast excess returns in the moments restrictions associated with Euler equations, and; ii) by pricing Lustig and Verdelhan (2007)’s foreign currency portfolios. Our results indicate that the relevant state variables that explain foreign-currency market asset prices are also the driving forces behind U.S. domestic assets behavior. Keywords: Equity Premium Puzzle, Forward Premium Puzzle, Return-Based Pricing Kernel.

Year

2011

Creators

Costa, Carlos Eduardo Issler, João Victor Matos, Paulo Rogério Faustino

Correlação entre a composição química de cones de guta-percha e sua qualidade obturadora de canais radiculares: avaliação de diferentes marcas comerciais

The chemical composition of eight commercially available of gutta-percha cones brands was determined and the results correlated with the apical seal ability. These brands were: (AnalyticÔ, DentsplyÔ, DiadentÔ, MetaÔ, ObturaÔ, OdusÔ, TanariÔ and UltimateÔ). The gutta-percha cones components (ZnO, BaSO4, gutta-percha, wax and resins) were initially obtained by Frideman et al 38 method. The composition of cones was obtained by gravimetric analysis, energy-dispersive X-ray microanalysis, X-ray diffraction and elemental analysis. The gutta-percha polymer was characterized by thermal analysis (TGA and DSC), intrinsic viscosity, gel permeation chromatography, infrared and nuclear magnetic resonance. The method described by Friedman et al 38 was appropriated to quantify gutta-percha and resin/wax components of cones, but led to overestimation of barium sulphate and zinc oxide. An average increase in the amount of barium sulfate of 3.5% in relation to the corrected BaSO4 mass value and of 43.6% in relation to cone mass was observed. Gutta-percha content range from 14.5 to 20.4% and zinc oxide from 62.8 to 84.3%. Barium sulphate was not detected in three of these brands (DentsplyÔ, OdusÔ and TanariÔ). TGA analysis shows that the inorganic residue obtained in this technique is similar of the inorganic residues observed in the gravimetric analysis. Crystal phases of gutta-percha polymer were identified by DSC. AnalyticÔ, DiadentÔ, MetaÔ, ObturaÔ, OdusÔ and TanariÔ brands presents endothermic peak characteristic of b-guttapercha. In the other two brands the polymer is present in the a-phase. Molar mass determination by viscometric analysis shows similar values of seven brands in the average of 1.0 x 105 to 1.6 x 105 g/mol, however the polymer present in the TanariÔ brand has lower molar mass (5.6 x 104 g/mol). Similar results were obtained by GPC. 11 The polymer present in the eight brands were analysed by IV and NMR, transpolyisoprene was identified as the main polymer component in the gutta-percha cones. The infiltration results of five brands (DentsplyÔ, TanariÔ, ObturaÔ, OdusÔ and AnalyticÔ ) indicates that the small amount of gutta percha and also the presence of the a-phase in the DentsplyÔ brand may be responsible for the high infiltration observed. A poor sealing ability was observed for brands with gutta-percha content lower than 16%.

Year

2012

Creators

Silva Júnior, João Batista Araújo

Environmental protection and economic growth

This paper explores the link between environmental policy and economic growth by employing an extension of the AK Growth Model. We include a state equation for renewable natural resources. We assume that the change in environmental regulations induces costs and that economic agents also derive some utility from capital stock accumulation vis-`a-vis the environment. Using the Hopf bifurcation theorem, we show that cyclical environmental policy strategies are optimal, providing theoretical support for the Environmental Kuznets Curve.

Year

2011

Creators

Teles, Vladimir Kuhl Arraes, Ronaldo de Albuquerque e

Obtenção e caracterização de revestimento de ZN-Mn em meio de sulfato

The development of alloys that are resistant to corrosion and good wear resistance led to several studies on the electrodeposition field. With the intention of carry out alloys with good mechanic properties, associated to a high corrosion resistance, Zn-Mn alloys have been frequently studied in the last years, once they offer better anticorrosive characteristics when compared to metallic zinc films, usually used in the conventional industry. This work aimed obtain and characterize Zn-Mn alloy electrodeposited on platinum electrode and metallic cooper from solutions composed by sulfate salts from the metals previously mentioned. Zn-Mn alloys were studied by using of cyclic and linear voltammetry, and also chronoamperommetry, in which all samples were obtained in bath without agitation, room temperature, 25º C, on different current densities. The physical and morphological structure of the alloys that have been obtained were analyzed by using technique such as scanning electronic microscopy (SEM) and X-ray dispersive energy (XDE), varying parameters such as: current density applied, pH, deposition temperature and reagents concentration in the bath. In order to analyze the chemical structure of the species formed on the alloy mentioned, a x-ray diffraction (XRD) technique was used with the samples obtained in cooper electrode. From the results obtained through voltammetric analyses, it is possible to determine the potential of reduction and oxidation of Zn-Mn alloy, which occurred separately to zinc and manganese. It was possible to observe that the manganese in the alloy appears as the oxide and the zinc as an isolated metal. Through XRD analysis, it was possible to determine the phases in which the Zn-Mn species appears in the alloy, and also isolated zinc and manganese. The best results were obtained when was applied 10mA.cm-2 current density; pH 6,0; room temperature and 1:1 proportion of zinc and manganese in the electrolytic bath.

Year

2012

Creators

Ferreira Júnior, José Milton

O ensino de biologia e química para alunos surdos no ensino médio da rede pública da cidade de Fortaleza : estudo de caso

The scientific and technological advances and changes that occur in society impose the need for a comprehensive initial training, as well as a constant improvement of those that are directly linked to the teaching-learning process. Thus, the technical and scientific knowledge related to chemistry and life sciences and the field of knowledge and teaching strategies, is to add features and discussions related to specific students. It is argued in this paper, the need to expand teacher training focused on the theme of education for children, youth and adults with disabilities - specifically the education of the deaf. It is known that the teacher acts in the neurobiological changes that produce learning, but the vast majority know how the brain works, what the specific needs and activities should be planned to enable the success of the process, even in deaf students, that have specific characteristics, especially language. This study was conducted in four public schools in the state of Fortaleza. Interviews were conducted with 10 teachers and 10 interpreters, and the application of two neuropsychological tests (Rey and NEUPSILIN) to 60 students (40 deaf and 20 listeners). As a result, there was the unpreparedness of teachers to work with this audience, noticeable by the absence of specific methodologies and the difficulty of interaction, since the teachers do not master the language, in addition to sign language for lack of terms specific to the disciplines of biology and chemistry. As for the interpreters were able to identify a specific area related to the unpreparedness of the subjects of Biology and Chemistry, and an exhaustive workload. This result revealed the gap between these professionals. With regard to students, the tests indicated that the perception and memory of deaf students are subtly than the standards specified in the tests. While students in the audience, the tests indicated a small gap of perception and memory. It is believed that this knowledge provides the teacher input into the development of strategies to facilitate the learning of deaf students, respecting their characteristics, in addition to direct a constant reflection of the practice, which may lead to effecting the necessary changes, thus providing improvement in the training of professionals and thus in education.

Year

2011

Creators

Monteiro, Josefa Hilda Siqueira

Métodos computacionais aplicados no estudo de fármacos

In this work we performed ab initio calculations on two drugs, benzonidazole and mebendazole, used on the treatment of parasitic infections. The calculations were divided into obtaining the vibrational modes Raman and infrared spectra, molecular dynamics and calculation of the potential energy distribution. We developed the software PEDCALC to calculate the potential energy distribution and classify the vibrational modes. The classification of the vibrational modes is done by comparing the calculated spectra with experimental spectra and the potential energy distribution. We showed that software PEDCALC can produce accurate results of the potential energy distribution, and it is essential tool in the classification of vibrational modes of any molecule. We performed molecular dynamics calculations in the dimer of mebendazole to show the exchange of hydrogen atoms between its monomers, so we observed the dynamics of the tautomerism of this molecule.

Year

2015

Creators

Alves, Daniel de Matos

Estudo da cadeia de suprimentos de portas prontas de madeira

This master's thesis investigated the flows of material and information among participants of the supply chain of pre-fabricated wooden doors. The Brazilian literature on the topic presents different studies on supply chain mapping, however, few of them discuss issues related to supply chains on the country's Northeastern region. The supply chain investigated was choosen based on previous research projects carried out by the Grupo de Pesquisa e Assessoria em Gerenciamento na Construção Civil (GERCON), a construction management research group at the Federal University of Ceará, Brazil. Previous studies carried out by GERCON researchers, on low-income housing projects, had revealed numerous problems related to wooden doors and windows. Using the results of previous studies as a starting point, this thesis studied the pre-fabricated wooden doors and their supply chain which have all of its components pre-assembled by the supplier. The use of pre-fabricated wooden doors would theoretically reduce the number of activities performed at the construction site, and would result in a shorter installation time. The two-phase research comprised a preliminary study and two in-depth case studies about pre-fabricated wooden doors. The author carried out the case studies in two high rising buildings (one residential and one commercial) in the city of Fortaleza, Brazil, in order to investigate the supply chain of pre-fabricated wooden doors. Value stream maps were developed based on direct observation of the processes involved to fabricate and install the product at the supplier‟s plant and the construction site respectively, photos, and interviews with different professionals at the plant and at the site. Wooden doors presented problems related to the installation and final product quality regardless of the type of project. Some advantages of prefabricated elements were lost due lack of trust between contractors and suppliers, lack of consideration of preconditions necessary for successful site installation, and lack of standardization and tolerance management resulted in suboptimal solutions during the installation phase. Special attention should be paid to the interfaces between the prefabricated element and the other parts of the project, current means and methods should be revisited if the project is to fully take advantage of prefabrication. The lack of open communication and low levels of trust amongst the supply chain actors result in enormous amounts of waste (e.g., rework, wasted time, unnecessary handling, unnecessary use of resources) and diminished value to the client.

Year

2011

Creators

Melo, Reymard Sávio Sampaio de

Estudo de compostos lamelares contendo Fe usando Espectroscopia Mössbauer de 57Fe e técnicas complementares

The structural and thermal decomposition properties of Mg-Fe and Co-Cu-Fe hy-drotalcites (HT) have been studied through thermogravimetric analysis, X ray powder diffraction (XRD), Fourier transform infrared spectroscopy and 57Fe MÄossbauer spectroscopy. In the Mg-Fe system, the destruction of the layered structure took place at about 300 oC. The broad peaks observed in the X ray diffractograms suggests that the resultant oxides constitute a solid solution. For samples treated at temperatures higher than 500 oC the formation of the MgO and MgFe2O4 formation of the MgO and MgFe2O4 spinel phases is observed. 57Fe MÄossbauer spectroscopy was employed to monitor the Fe chemical environment for the samples annealed at different temperatures (100-900 oC). In situ XRD experiments revealed that the HTs start an interlayer contraction at about 180 oC. This phenomenon is identifed as being due to a grafting process for which the interlamellar anions attach to the layers through a covalent bond. The reconstruction of the Mg-Fe HTs was also investigated and its e±ciency depends on the thermal annealing temperature and on the Mg/Fe ratio. The structure of the reconstructed samples was found to be exactly the same as the parent structure. The in situ 57Fe MÄossbauer experiments were performed in the 100-500 oC temperature range con¯rm an increasing structural disorder in this temperature range. The quadrupolar splitting indicates that the maximum disorder occurs at 300 oC. Regarding the Co-Cu-Fe ternary system we have observed that due to the strong Jahn-Teller e®ect the Cu-Fe layered system is stabilized only in the presence of Co2+. At low Co2+ contents, additional phases are segregated in the solids. X ray patterns di®raction The structural and thermal decomposition properties of Mg-Fe and Co-Cu-Fe hydrotalcites (HT) have been studied through thermogravimetric analysis, X ray powder diffraction (XRD), Fourier transform infrared spectroscopy and 57Fe Mossbauer spectroscopy. In the Mg-Fe system, the destruction of the layered structure took place at about 300 oC. The broad peaks observed in the X ray diffractograms suggests that the resultant oxides constitute a solid solution. For samples treated at temperatures higher than 500 oC the formation of the MgO and MgFe2O4 formation of the MgO and MgFe2O4 spinel phases is observed. 57Fe Mossbauer spectroscopy was employed to monitor the Fe chemical environment for the samples annealed at different temperatures (100-900 oC). In situ XRD experiments revealed that the HTs start an interlayer contraction at about 180 oC. This phenomenon is identified as being due to a grafting process for which the interlamellar anions attach to the layers through a covalent bond. The reconstruction of the Mg-Fe HTs was also investigated and its efficiency depends on the thermal annealing temperature and on the Mg/Fe ratio. The structure of the reconstructed samples was found to be exactly the same as the parent structure. The in situ 57Fe Mossbauer experiments were performed in the 100-500 oC temperature range confirm an increasing structural disorder in this temperature range. The quadrupolar splitting indicates that the maximum disorder occurs at 300 oC. Regarding the Co-Cu-Fe ternary system we have observed that due to the strong Jahn-Teller effect the Cu-Fe layered system is stabilized only in the presence of Co2+. At low Co2+ contents, additional phases are segregated in the solids. X ray patterns diffraction show the presence of Cu(OH)2 and CuO. The decomposition process was investigated by in situ X ray, in situ Mossbauer and FTIR experiments. By increasing the temperature from 25 oC up to 180 oC we observed that the structural disorder increases. This effect has been likely attributed to the Co 2+ to Co3+ oxidation since thermal decomposition was carried out under static air atmosphere. Part of the Co3+ cations could migrate to the interlayer region, thus forming a metastable compound that still has a layered structure. Collapse of the layered structure was observed at about 200 oC. By further increasing the temperature the system becomes more crystalline and the formation of Co3O4 is observed in the X ray patterns. In Cu-rich HT, some of the carbonate anions are released at temperatures higher than 550 oC and this phenomenon is attributed to the formation of a carbonate-rich phase. The specific surface area data present its highest values in the temperature range where the collapse of the layered structure takes place.

Year

2015

Creators

Gouveia, Daniel Xavier

Estudo do efeito de diferentes granulometrias no comportamento mecânico de misturas asfálticas densas descontínuas tipo Stone Matrix Asphalt (SMA)

In Brazilian roadways, which concentrate 96.2% of the passengers and 61.8% of the cargo, it is clear the deterioration of asphalt pavements caused by an increasing volume and weight of the vehicle loadings. This configuration strongly contributes to pavement distresses, specially rutting and fatigue cracking. On another hand, the State of Ceará shows a lack of paved roadways, with only 16.0% of paved roads. The Stone Matrix Asphalt (SMA) mixture appeared a few years ago as a solution for minimizing distresses on roadways with high traffic levels. Some researches, however, demonstrate that SMA mixtures with small Nominal Maximum Aggregate Sizes (NMAS) offer similar performances to SMA mixtures with usual NMAS. The objective of the present research was to design SMA mixtures with different gradations in order to study some characteristics of this type of mixture, investigating the effect (i) of the NMAS, (ii) of the percentage of aggregate passing in sieve N. 4 (4.75mm) for 12.5mm NMAS SMA mixtures and (iii) of the compaction type (Marshall × Superpave) on the mechanical behavior of the mixtures. The mixtures were evaluated by (i) resilient modulus, (ii) indirect tensile strength, (iii) fatigue life (stress controlled), (iv) resistance to moisture damage and (v) Cantabro abrasion. The results support the idea that SMA mixtures with small NMAS behave similar to those with usual NMAS. Furthermore, the 4.75mm NMAS SMA appears to be a potential solution for roadways in Ceará, considering the traffic configuration of this state.

Year

2011

Creators

Oliveira Filho, Clonildo Moreira Sindeaux de

Estudo da influência dos parâmetros operacionais na eletrodeposição de camadas eletrocatalíticas de ligas de Ni-Fe.

The present work shows the study of the ultrasound irradiation influence in the electrodeposition of Ni-Fe coatings. The electrocatalytic performance of these coatings for the hydrogen evolution reaction (her) in alkaline medium was also evaluated. The Ni-Fe coatings were obtained from plating solutions containing 0.06 mol.dm-3 Ni2SO4.6H2O, 0.48 mol.dm-3 Na3C3H5O7.2H2O, 0.71 mol.dm-3 Na2CO3 and 0.16 mol.dm-3 (bath 1) and 0.04 mol.dm-3 FeSO4.7H2O (bath 2). It was also added 8.4 mL L-1 H2SO4 to maintain the pH below 1. The electrodepositions were carried out under galvanostatic control in the range of 10 mA cm-2 to 50 mA cm-2, at room temperature (≈ 28ºC) and at 55ºC in the presence and in the absence of ultrasound irradiation. All coatings were deposited on disk mild steel substrate with an exposed geometric area of 0.7 cm2. The hydrogen evolution reaction was studied in 0.5 mol.dm-3 NaOH. In all electrochemical experiments Pt was the auxiliary electrode and Hg/HgO, OH- (0,5 mol.dm-3) was the reference one. The coatings ware characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and the electrocatalytic properties of the Ni-Fe coating were evaluated by Tafel polarization and long-term performance tests. The results showed that the use of the ultrasound irradiation leads to an increase of the Fe content in the electrodeposits. Additionally, the coatings obtained in presence of ultrasound also present the best performance for her.

Year

2012

Creators

Sousa, Josenir Barreto de

Eletrodeposição de CuNi em meio de sulfato. uma nova abordagem

The interest for the electroplating of CuNi and its multiple layers is proportionate to the properties of these materials, such as: mechanical resistance to corrosion, mechanical (high tractive force, malleability and ductility) and magnetic properties, beyond its catalytic properties. The voltammetric results suggest that CuNi is electroplated, forming a solid solution. By cyclic voltammetry, the influence of different electrolytic bath in the electroplating of CuNi was investigated, where if it observed the formation of more noble alloys in sulphate baths and tartarate and less noble alloys in citrate and citrate/tartarate medium. Hydrodynamic experiments had been carried through, where it was verified for CuNi in sulphate and tartarate a transport of diffusional mass; for CuNi in citrate and citrate/tartarate was not observed the formation of diffusional plateau, suggesting a transport of mass by charge transference. By dispersive energy of rays-X, the atomic percentage of the constituent of the alloy was determined, where CuNi alloy in sulphate bath and tartarate present a percentage of nickel about 20% and in citrate and citrate/tartarate medium, the percentage of nickel falls espectively for 2% and 4%. By spectrometry of absorption of UV-Vis it was calculated the _ values for individual metals and CuNi, being found low values, indicating that as much the individual metals as the alloy in the different electrolytic transitions d-d type. It was made a comparative study between the electrochemical techniques (Linear Sweep Voltammetry, Chronoamperometry) and Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES), for copper determination. The copper taxes determined for both methods are near, presenting small variations, where the gotten errors are distributed in a random way presenting an average value of 2,56%. The carried through statistical tests had shown that the gotten results are in a reliable band of 95%. Based in these results it is possible to affirm that the used electrochemical techniques are efficient in the copper determination, making possible, thus, the validation of these for ICP-OES.

Year

2012

Creators

Pacheco, Luisa Célia Melo