Mostrando recursos 1 - 20 de 221

  1. Morfodinâmica praial : uma breve revisão

    Calliari, Lauro Julio; Muehe, Dieter Carl Ernst Heino; Hoefel, Fernanda Gemael; Toldo Junior, Elirio Ernestino
    Desde o início dos anos 30 perfis de praia foram classificados em um dos dois tipos: perfis de tempestade ou perfis de ondulação associados, respectivamente, com ondas de alta e baixa esbeltez. Mudanças no perfil praial envolvem muitas variáveis, tornando muito difícil a formulação de modelos de prediçâo de comportamento praial. Somente a partir da década de 70, as características dos sedimentos c os processos de transformação de ondas operantes na plataforma interna e antepraia, acoplados com a morfologia tridimensional e a hidrodinâmica da praia, começaram a ser estudados de maneira integrada. Tais estudos levaram a um melhor entendimento do...

  2. Morfodinâmica praial : uma breve revisão

    Calliari, Lauro Julio; Muehe, Dieter Carl Ernst Heino; Hoefel, Fernanda Gemael; Toldo Junior, Elirio Ernestino
    Desde o início dos anos 30 perfis de praia foram classificados em um dos dois tipos: perfis de tempestade ou perfis de ondulação associados, respectivamente, com ondas de alta e baixa esbeltez. Mudanças no perfil praial envolvem muitas variáveis, tornando muito difícil a formulação de modelos de prediçâo de comportamento praial. Somente a partir da década de 70, as características dos sedimentos c os processos de transformação de ondas operantes na plataforma interna e antepraia, acoplados com a morfologia tridimensional e a hidrodinâmica da praia, começaram a ser estudados de maneira integrada. Tais estudos levaram a um melhor entendimento do...

  3. Ajuste de modelo para quantificar o efeito de plantas daninhas e época de semeadura no rendimento de soja

    Rizzardi, Mauro Antonio; Fleck, Nilson Gilberto; Riboldi, João; Agostinetto, Dirceu
    O objetivo deste trabalho foi ajustar e validar um modelo matemático baseado em densidades de picão-preto (Bidens spp.) e de guanxuma (Sida rhombifolia L.), integrando a época de semeadura da soja após a dessecação da cobertura vegetal, para quantificar perdas de rendimento de grãos. Foram conduzidos quatro experimentos, em Passo Fundo e Eldorado do Sul. Os tratamentos constaram de densidades de picão-preto ou de guanxuma e de épocas de semeadura da soja em relação à data de dessecação da cobertura vegetal. Nos experimentos com picão-preto, a semeadura da soja foi realizada 3, 7 e 11 dias após dessecação (DAD) da...

  4. Ajuste de modelo para quantificar o efeito de plantas daninhas e época de semeadura no rendimento de soja

    Rizzardi, Mauro Antonio; Fleck, Nilson Gilberto; Riboldi, João; Agostinetto, Dirceu
    O objetivo deste trabalho foi ajustar e validar um modelo matemático baseado em densidades de picão-preto (Bidens spp.) e de guanxuma (Sida rhombifolia L.), integrando a época de semeadura da soja após a dessecação da cobertura vegetal, para quantificar perdas de rendimento de grãos. Foram conduzidos quatro experimentos, em Passo Fundo e Eldorado do Sul. Os tratamentos constaram de densidades de picão-preto ou de guanxuma e de épocas de semeadura da soja em relação à data de dessecação da cobertura vegetal. Nos experimentos com picão-preto, a semeadura da soja foi realizada 3, 7 e 11 dias após dessecação (DAD) da...

  5. Cordão Formation: loess deposits in the southern coastal plain of the state of Rio Grande do Sul, Brazil

    Lopes, Renato Pereira; Dillenburg, Sergio Rebello; Schultz, Cesar Leandro
    Loess consists of silt-dominated sediments that cover ~10% of the Earth’s surface. In southern South America it occurs in Argentina, Bolivia, Paraguay and Uruguay, and its presence in southern Brazil was never studied in detail. Here is proposed a new lithostratigraphic unit, Cordão Formation, consisting of loess deposits in the southern Brazilian coastal plain. It consists of fine-very fine silt with subordinate sand and clay, found mostly in lowland areas between Pleistocene coastal barriers. These sediments are palecolored (10YR hue) and forms ~1,5-2,0 meter-thick stable vertical walls. The clay minerals include illite, smectite, interstratified illite/smectite and kaolinite, the coarser fraction...

  6. Cordão Formation: loess deposits in the southern coastal plain of the state of Rio Grande do Sul, Brazil

    Lopes, Renato Pereira; Dillenburg, Sergio Rebello; Schultz, Cesar Leandro
    Loess consists of silt-dominated sediments that cover ~10% of the Earth’s surface. In southern South America it occurs in Argentina, Bolivia, Paraguay and Uruguay, and its presence in southern Brazil was never studied in detail. Here is proposed a new lithostratigraphic unit, Cordão Formation, consisting of loess deposits in the southern Brazilian coastal plain. It consists of fine-very fine silt with subordinate sand and clay, found mostly in lowland areas between Pleistocene coastal barriers. These sediments are palecolored (10YR hue) and forms ~1,5-2,0 meter-thick stable vertical walls. The clay minerals include illite, smectite, interstratified illite/smectite and kaolinite, the coarser fraction...

  7. Investigation of freshwater sponges spicules deposits in a karstic lake in Brazil

    Machado, Vagner da Silva; Ribeiro, Cecilia Volkmer; Iannuzzi, Roberto
    The environmental conditions which contributed to the formation of the notorious quaternary deposits of freshwater sponge spicules in karstic lentic environments in Brazil have been subject of some speculation. No investigation has yet been conducted to test whether these deposits currently originate in karstic lakes. To provide for such an investigation, Serra Negra Lake, which is formed on an ultramafic-alkaline-carbonatite dome at central western Brazil, close to the area of occurrence of the paleo-deposits was selected for the study. Bottom sediments were sampled at 10 stations across the lake, and water was sampled at five of the stations, in June/2011...

  8. Investigation of freshwater sponges spicules deposits in a karstic lake in Brazil

    Machado, Vagner da Silva; Ribeiro, Cecilia Volkmer; Iannuzzi, Roberto
    The environmental conditions which contributed to the formation of the notorious quaternary deposits of freshwater sponge spicules in karstic lentic environments in Brazil have been subject of some speculation. No investigation has yet been conducted to test whether these deposits currently originate in karstic lakes. To provide for such an investigation, Serra Negra Lake, which is formed on an ultramafic-alkaline-carbonatite dome at central western Brazil, close to the area of occurrence of the paleo-deposits was selected for the study. Bottom sediments were sampled at 10 stations across the lake, and water was sampled at five of the stations, in June/2011...

  9. Dynamic and resuspension by waves and sedimentation pattern definition in low energy environments Guaíba Lakes (Brazil).

    Nicolodi, João Luiz; Toldo Junior, Elirio Ernestino; Farina, Leandro
    Little research has been undertaken into sediment dynamics in lakes, and most of it only analyses particular aspects such as the texture of the sediments. In this study, the characteristics of the wave field in Guaíba Lake are investigated. The parameters significant wave height (Hs), period (T) and direction of wave propagation are examined together with their relation to the resuspension of sediments at the bottom. For this purpose, the mathematical model SWAN (Simulating Waves Nearshore) has been validated and employed. The results pointed out that the highest waves modeled reached 0.55 m at a few points in the lake,...

  10. Petrologia do Granito Chasqueiro, região de Arroio Grande, sudeste do Escudo Sul-Rio-Grandense

    Vieira, Daniel Triboli; Koester, Edinei; Bertotti, Anelise Losangela
    O Granito Chasqueiro aflora como campos de matacões e lajeados, que em planta constituem um corpo alongado segundo N50oE com área de aproximadamente 400 km2, localizado no sul da porção oriental do Escudo Sul-Rio-Grandense. Compreende de monzo a sienogranito, leucocrático de cor cinza-clara e textura porfirítica com megacristais de K-feldspatos em matriz equigranular, hipidiomórfica grossa, composta por quartzo, K-feldspato, plagioclásio, biotita, hornblenda, minerais opacos e acessórios. Os megacristais atingem proporções modais entre 30,0 e 60,0%, e variam entre 4 e 8 cm, que com os minerais máficos da matriz evidenciam uma foliação de fluxo magmático subvertical bem desenvolvida que transaciona...

  11. Petrologia do Granito Chasqueiro, região de Arroio Grande, sudeste do Escudo Sul-Rio-Grandense

    Vieira, Daniel Triboli; Koester, Edinei; Bertotti, Anelise Losangela
    O Granito Chasqueiro aflora como campos de matacões e lajeados, que em planta constituem um corpo alongado segundo N50oE com área de aproximadamente 400 km2, localizado no sul da porção oriental do Escudo Sul-Rio-Grandense. Compreende de monzo a sienogranito, leucocrático de cor cinza-clara e textura porfirítica com megacristais de K-feldspatos em matriz equigranular, hipidiomórfica grossa, composta por quartzo, K-feldspato, plagioclásio, biotita, hornblenda, minerais opacos e acessórios. Os megacristais atingem proporções modais entre 30,0 e 60,0%, e variam entre 4 e 8 cm, que com os minerais máficos da matriz evidenciam uma foliação de fluxo magmático subvertical bem desenvolvida que transaciona...

  12. Trace analysis of carbazole in commercial diesel by using adsorption on activated biochar from rice husk pyrolysis

    Maciel, Gabriela Pereira da Silva; Lazzari, Eliane; Bjerk, Thiago Rodrigues; Ahmad, Samir M.; Carvalho, Ana Paula Baptista de; Nogueira, José Manuel Florêncio; Caramão, Elina Bastos
    The valorization of rice husk biochar obtained by pyrolysis was studied by production high quality activated carbon. Activated carbon (AC) chemically treated by K2CO3, was used as sorbent phase in bar adsorptive microextraction followed by comprehensive two-dimensional gas chromatography coupled to a quadrupole mass spectrometer analysis (BAμE/GC×GC-qMS) for trace analysis of carbazole in commercial diesel. The prepared AC was characterized by N2 adsorption, SEM-EDS and pHPZC. Assays of nitrogen adsorption isotherm demonstrated that the AC presented microporosity and the Density Functional Theory Calculation was applied to obtain information concerning the micropore size distribution. The BET surface area and total pore...

  13. Trace analysis of carbazole in commercial diesel by using adsorption on activated biochar from rice husk pyrolysis

    Maciel, Gabriela Pereira da Silva; Lazzari, Eliane; Bjerk, Thiago Rodrigues; Ahmad, Samir M.; Carvalho, Ana Paula Baptista de; Nogueira, José Manuel Florêncio; Caramão, Elina Bastos
    The valorization of rice husk biochar obtained by pyrolysis was studied by production high quality activated carbon. Activated carbon (AC) chemically treated by K2CO3, was used as sorbent phase in bar adsorptive microextraction followed by comprehensive two-dimensional gas chromatography coupled to a quadrupole mass spectrometer analysis (BAμE/GC×GC-qMS) for trace analysis of carbazole in commercial diesel. The prepared AC was characterized by N2 adsorption, SEM-EDS and pHPZC. Assays of nitrogen adsorption isotherm demonstrated that the AC presented microporosity and the Density Functional Theory Calculation was applied to obtain information concerning the micropore size distribution. The BET surface area and total pore...

  14. Trace analysis of carbazole in commercial diesel by using adsorption on activated biochar from rice husk pyrolysis

    Maciel, Gabriela Pereira da Silva; Lazzari, Eliane; Bjerk, Thiago Rodrigues; Ahmad, Samir M.; Carvalho, Ana Paula Baptista de; Nogueira, José Manuel Florêncio; Caramão, Elina Bastos
    The valorization of rice husk biochar obtained by pyrolysis was studied by production high quality activated carbon. Activated carbon (AC) chemically treated by K2CO3, was used as sorbent phase in bar adsorptive microextraction followed by comprehensive two-dimensional gas chromatography coupled to a quadrupole mass spectrometer analysis (BAμE/GC×GC-qMS) for trace analysis of carbazole in commercial diesel. The prepared AC was characterized by N2 adsorption, SEM-EDS and pHPZC. Assays of nitrogen adsorption isotherm demonstrated that the AC presented microporosity and the Density Functional Theory Calculation was applied to obtain information concerning the micropore size distribution. The BET surface area and total pore...

  15. Avaliação de fragmentos de lenhos carbonizados de araucariaceae por meio de termogravimetria e infravermelho associadas à análise multivariada

    Lara, Daniela Muller de; Bresciani, Laís; Osterkamp, Isa Carla; Hilgemann, Maurício; Ethur, Eduardo Miranda; Jasper, André; Ferrão, Marco Flôres; Uhl, Dieter; Stulp, Simone
    The aim of the study is to evaluate the physical and chemical changes that occur on wood fragments submitted to different temperatures, verifying their influence on significant chemical characteristics in the forming process. Carbonization process in muffle associated to the techniques of Thermogravimetry, Fourier Transform Infrared Spectroscopy (FTIR) and multivariate analysis. The analyses were performed on 3 replicates for each burn temperature. The temperature of the thermal muffle process was in every 50 °C, from 200 °C to 600 °C. TGA were performed under nitrogen atmosphere, using a heating ramp from 25 °C min-1 to 995 °C. A range between...

  16. O programa de apoio à graduação em química (pag-química) e sua contribuição para a democratização e permanência dos estudantes no ensino superior

    Gregório, José Ribeiro; Leite, Clarice Caldeira; Leal, Bárbara Caroline; Nitschke, William Kelbert; Pederzolli, Fernanda Rosi Soares; Borba, Katiúscia Machado Nobre; Fraga, Marcus Vinícius Barcellos de; Silva, Cláudia de Brito da
    A evasão e a retenção universitária vêm se impondo, ao longo do tempo, como uma realidade cada vez mais ostensiva no âmbito do ensino de graduação dos cursos de ciências exatas. Com o intuito de oferecer alternativas para erradicar este problema, ações que visam à democratização e à permanência dos estudantes de ensino superior vêm sendo adotadas em algumas instituições de ensino federal brasileiras. Neste artigo descreve-se a contribuição do programa PAG-Química (Programa de Apoio à Graduação em Química), proposto pela Universidade Federal do Rio Grande do Sul (UFRGS) no âmbito do programa REUNI (Reestruturação das Universidades Federais), que tem...

  17. Searches for transverse momentum dependent ow vector uctuations in Pb-Pb and p-Pb collisions at the LHC

    Acharya, Shreyasi; Gay Ducati, Maria Beatriz; Pereira, Luis Gustavo; Pezzi, Rafael Peretti; ALICE Collaboration
    The measurement of azimuthal correlations of charged particles is presented for Pb{Pb collisions at p sNN = 2.76TeV and p{Pb collisions at sNN = 5.02TeV with the ALICE detector at the CERN Large Hadron Collider. These correlations are measured for the second, third and fourth order ow vector in the pseudorapidity region < 0:8 as a function of centrality and transverse momentum pT using two observables, to search for evidence of pT-dependent ow vector uctuations. For Pb{Pb collisions at 2.76TeV, the measurements indicate that pT-dependent uctuations are only present for the second order ow vector. Similar results have been found...

  18. Anomalous evolution of the near-side jet peak shape in Pb-Pb collisions at √sNN=2.76 TeV

    Adam, Jaroslav; Gay Ducati, Maria Beatriz; ALICE Collaboration
    The measurement of two-particle angular correlations is a powerful tool to study jet quenching in a pT region inaccessible by direct jet identification. In these measurements pseudorapidity (Δη) and azimuthal (Δφ) differences are used to extract the shape of the near-side peak formed by particles associated with a higher pT trigger particle (1 < pT;trig < 8 GeV=c). A combined fit of the near-side peak and long-range correlations is applied to the data allowing the extraction of the centrality evolution of the peak shape in Pb-Pb collisions at sNN p ¼ 2.76 TeV. A significant broadening of the peak in...

  19. Ionic liquid assisted hydrothermal syntheses of Au doped TiO2 NPs for efficient visible-light photocatalytic hydrogen production from water, electrochemical detection and photochemical detoxification of hexavalent chromium (Cr6+)

    Ravishankar, Thammadihalli Nanjundaiah; Vaz, Maurício de Oliveira; Ramakrishnappa, Thippeswamy; Teixeira, Sergio Ribeiro; Dupont, Jairton
    Au/TiO2 NPs have been successfully prepared at 130 C in one day using an ionic liquid assisted hydrothermal method using methoxyethyl methyl imidazolium methanesulfonate as the ionic liquid, titanium(IV) isopropoxide and tetrachloroaurate(III) trihydrate as precursors. Physico-chemical properties of the obtained photocatalysts were investigated via thorough characterizations. The framework substitution of Au in TiO2 NPs was established by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and energy dispersive X-ray spectroscopy (EDS) techniques. X-ray diffraction (XRD) and transmission electron microscopy (TEM) image results confirmed the anatase phase and nanocrystalline nature of Au/TiO2. The optical properties revealed an extended tailing of the absorption...

  20. Evolution of the longitudinal and azimuthal structure of the near-side jet peak in Pb-Pb collisions at √ sNN = 2.76 TeV

    Adam, Jaroslav; Gay Ducati, Maria Beatriz; ALICE Collaboration
    In two-particle angular correlation measurements, jets give rise to a near-side peak, formed by particles associated to a higher-pT trigger particle. Measurements of these correlations as a function of pseudorapidity ( η) and azimuthal ( ϕ) differences are used to extract the centrality and pT dependence of the shape of the near-side peak in the pT range 1 < pT < 8 GeV/c in Pb-Pb and pp collisions at √ sNN = 2.76 TeV. A combined fit of the near-side peak and long-range correlations is applied to the data and the peak shape is quantified by the variance of the...

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