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Showing papers by "Federal University of Roraima published in 2013"


Journal ArticleDOI
TL;DR: The results show that fluorination tends to produce defective areas on the graphene membranes with significant distortions of carbon-carbon bonds, which may explain the broad distribution of the structural lattice parameter values experimentally observed.
Abstract: We report here a fully reactive molecular dynamics study on the structural and dynamical aspects of the fluorination of graphene membranes (fluorographene). Our results show that fluorination tends to produce defective areas on the graphene membranes with significant distortions of carbon-carbon bonds. Depending on the amount of incorporated fluorine atoms, large membrane holes were observed due to carbon atom losses. These results may explain the broad distribution of the structural lattice parameter values experimentally observed. We have also investigated the effects of mixing hydrogen and fluorine atoms on the graphene functionalization. Our results show that, when in small amounts, the presence of hydrogen atoms produces a significant decrease in the rate of fluorine incorporation onto the membrane. On the other hand, when fluorine is the minority element, it produces a significant catalytic effect on the rate of hydrogen incorporation. We have also observed the spontaneous formation of new hybrid structures with different stable configurations (chair-like, zigzag-like and boat-like) which we named fluorographane.

84 citations


Journal ArticleDOI
TL;DR: The diazotrophic B. vietmaniensis strain AR1122 was a good biofertilizer candidate for inoculation of traditional rice varieties and therefore should be used for further studies to confirm the strain-genotype effect envisaging a sustainable rice crop system mainly in the Northeast region of Brazil.

53 citations


Journal ArticleDOI
TL;DR: Four new d-xylose fermenting yeast species of the clade Spathaspora were recovered from rotting-wood samples in a region of Amazonian forest, Northern Brazil, and all are able to ferment d-Xylose during aerobic batch growth in rich YP medium, albeit with differing efficiencies.
Abstract: Four new d-xylose fermenting yeast species of the clade Spathaspora were recovered from rotting-wood samples in a region of Amazonian forest, Northern Brazil. Three species produced unconjugated asci with a single elongated ascospore with curved ends. These species are described as Spathaspora brasiliensis, Spathaspora suhii and Spathaspora roraimanensis. Two isolates of an asexually reproducing species belonging to the Spathaspora clade were also obtained and they are described as Spathaspora xylofermentans. All these species are able to ferment d-xylose during aerobic batch growth in rich YP (1 % yeast extract, 2 % peptone and 2 % D-xylose) medium, albeit with differing efficiencies. The type strains are Spathaspora brasiliensis sp. nov UFMG-HMD19.3 (=CBMAI 1425=CBS 12679), Spathaspora suhii sp. nov. UFMG-XMD16.2 (=CBMAI 1426=CBS 12680), Spathaspora roraimanensis sp. nov. UFMG-XMD23.2 (CBMAI 1427=CBS 12681) and Spathaspora xylofermentans sp. nov. UFMG-HMD23.3 (=CBMAI 1428=CBS 12682).

44 citations


Journal ArticleDOI
TL;DR: The aquatic flora of Northeastern Brazil exhibits high species richness; however, there is a scarcity of records of aquatic macrophytes for the States of Alagoas, Rio Grande do Norte, Maranhao, Sergipe and Piaui.
Abstract: Aquatic plants have great influence on the structure and dynamics of aquatic ecosystems, thereby contributing considerably to biodiversity. In Brazil, knowledge of the biodiversity of aquatic macroflora is still limited. We present a checklist of aquatic macrophytes occurring in the northeastern region of Brazil through a bibliographic search. We recorded a total of 412 species, 217 genera and 72 families. The most representative families were Cyperaceae (70 species), Poaceae (38), Fabaceae (27) and Asteraceae (20). The States with highest number of species were Pernambuco (370), Bahia (360), Ceara (267) and Paraiba (261). The best-represented life forms were amphibious (193 species) and emergent (100). The aquatic flora of Northeastern Brazil exhibits high species richness; however, there is a scarcity of records of aquatic macrophytes for the States of Alagoas, Rio Grande do Norte, Maranhao, Sergipe and Piaui.

23 citations


Journal ArticleDOI
03 May 2013
TL;DR: A nutricao adequada da plântula durante a fase de viveiro e determinante for reduzir o tempo de transplantio e pegamento no campo is considered in this paper.
Abstract: A nutricao adequada da plântula durante a fase de viveiro e determinante para reduzir o tempo de transplantio e pegamento no campo. O cedro doce, embora seja explorado comercialmente, carece de informacoes cientificas acerca do seu processo produtivo, sobretudo na fase de viveiro. Objetivou-se, portanto, com esse estudo, avaliar dois niveis de correcao da acidez do substrato com calcario dolomitico (PRNT 100%) e cinco doses de potassio na forma de KCl (0; 5; 10; 15 e 30 mg planta-1 de K2O), aplicadas em cobertura, por meio foliar, para mudas de cedro doce em estagio inicial de desenvolvimento, cultivadas em ambiente protegido. O delineamento experimental foi o inteiramente casualizado, em esquema fatorial 2 x 5, com quatro repeticoes, perfazendo um total de 400 parcelas experimentais. Cada parcela experimental foi representada por 10 plantas. Apos 50 dias de emergencia avaliaram-se: altura da parte aerea (ALT), comprimento da raiz (CR), diâmetro do coleto (DC), biomassa fresca e seca da parte aerea e da raiz (BFPA; BSPA; BFRA; BSRA) e os indices: ALT/DC; ALT/BSPA; BSRA/BSPA e Indice de Qualidade de Dickson (IQD). Concluiu-se que os fatores em estudo atuaram na qualidade da muda de modo independente; o efeito da calagem restringiu-se as variaveis relacionadas a raiz; as doses de potassio determinaram incrementos positivos nas variaveis ALT, CR, DC, BFPA, BSPA, BFRA, BSRA e no indice IQD. Nos indices ALT/DC; ALT/ BSPA e BSRA/BSPA os incrementos foram negativos em relacao as dosagens potassicas utilizadas. As doses estudadas ficaram aquem da demanda nutricional da muda, indicando que o cedro doce tem elevada demanda por K.

18 citations


Journal ArticleDOI
TL;DR: In this paper, the half-life of diuron was determined in five soils (Red-Yellow Latosols, Red Latosol, and Yellow Latosolis), with different pH values.
Abstract: The distribution and dissipation of herbicides on soils are dynamic and unique processes for each soil-herbicide relation. In this research, the half-life of diuron was determined in five soils (Red-Yellow Latosol, Red Latosol, and Yellow Latosol), with different pH values. Diuron concentrations were determined in samples of each soil collected at eight different times (1, 8, 15, 22, 36, 66, 96 and 156 days after herbicide application at 3.0kg ha-1). Part of each soil sample was used to quantify diuron by high performance liquid chromatography. The other part of soil sample was used to do biological tests in order to confirm the results of chromatographic analysis. It was found that the persistence of diuron is dependent on the physical and chemical soil attributes. However, the correction of soil pH favored only herbicide degradation in sandy soils with low organic matter content. The half-life of diuron in soils ranged from 40 to 91 after its application and it was higher in soil with higher organic matter content. The biological tests confirmed these results and they were efficient and complementary to the chromatographic analysis.

15 citations


Journal ArticleDOI
TL;DR: The Box-PCR profiles showed that the bacterial isolates obtained in this study presented a low similarity with the reference strains belonging to the Herbaspirillum, Azospirillum and Burkholderia genus, indicating that O. glumaepatula is colonized by a high diverse diazotrophic community in the Brazilian Amazon.
Abstract: The association of wild grasses with diazotrophic bacteria in Brazilian biomes is poorly understood. The isolation and characterization of bacteria associated with wild grasses can contribute to understand the diazotrophic ecology as well as to identify bacteria with biotechnological applications. In this study, we isolated and characterized diazotrophic bacterial isolates from Oryza glumaepatula collected in Cerrado and Forest areas of the Amazon in Roraima State, Brazil. Healthy O. glumepatula plants were collected at five sampling sites at Forest and seven at Cerrado, respectively. The plants were collected at the Cerrado areas in September 2008 while the Forest plants were collected in June/2008 and April/2009. The plants and the soil adhering to the roots were transferred to pots and grown for 35 days in greenhouse conditions. During the harvest, the shoots and the roots were crushed separately in a saline solution; the suspension was diluted serially and inoculated in Petri dishes containing Dyg’s medium. All distinct bacterial colonies were purified in the same medium. The diazotrophic capacity of each bacterium in microaerophilic conditions was assessed in semisolid BMGM medium. In addition, the pellicles forming bacterial isolates were also evaluated by PCR amplification for nifH gene. The diversity of nifH+ bacteria was analyzed by Box-PCR fingerprinting. For selected strains, the growth promoting capacity of O. sativa as a model plant was also evaluated. A total of 992 bacterial isolates were obtained. Fiftyone bacteria were able to form pellicles in the semisolid medium and 38 also positively amplified the 360bp nifH gene fragment. Among the 38 nifH+ isolates, 24 were obtained from the shoots, while 14 originated from the roots. The Box-PCR profiles showed that the bacterial isolates obtained in this study presented a low similarity with the reference strains belonging to the Herbaspirillum, Azospirillum and Burkholderia genus. The growthpromoting ability was confirmed for at least five isolates. For these bacteria, the root and shoot growing results showed higher increases when compared to those observed in plants inoculated with the evaluated reference strains. These results indicate that O. glumaepatula is colonized by a high diverse diazotrophic community in the Brazilian Amazon. Further investigations are now being carried out to determine the taxonomic positions of these isolates and their growth promoting mechanisms.

14 citations


Journal ArticleDOI
TL;DR: In this paper, the authors described and collected 29 soil profiles according with the main vegetation types of Campinaranas and Forests of PARNA Virua and surroundings, in an integrated vision of the landscape and, additionally, estimate the carbon stocks in soils and geo-environments.
Abstract: The Virua National Park (PARNA Virua) occupies 227.011 ha, in the region of the low 'Branco' river, in Roraima state. This area includes an extensive mosaic of complex seasonally flooded forested and non- forested environments. The present work aimed to characterize pedological aspects and identify the geo- environmental units of the Park and surroundings, in an integrated vision of the landscape and,additionally, estimate the carbon stocks in soils and geo-environments. We described and collected 29 soil profiles according with the main vegetation types of Campinaranas and Forests of PARNA Virua and surroundings. The main soil classes are: Espodossolo Humiluvico, Neossolo Quartzarenico, Neossolo Fluvico, Neossolo Litolicos, Latossolo Vermelho-Amarelo, Latossolo Vermelho, Cambissolo Haplico, Cambissolo Fluvico, Gleissolo Haplico and Plintossolo Haplico. The soils present an spatial distribution marked by abrupt limits and close association with the vegetation type. We identified three pedo-environments: (1) sandy soils of the Campinaranas; (2) soils associated with the inselbergs and adjacencies; and (3) alluvial soils. We mapped and described 18 geoenvironmental units in PARNA Virua National Park and surroundings. The main geo- environments are: i) Sandy plains and Paleodunes with grassy and arborous Campinarana on 'Neossolos Quartzarenicos hidromorficos' and 'Espodossolos'; and Floodplains and; ii) Terraces with Igapo Forest on sandy hydromorphic soils, occupying 24.6 % and 20.1 % of the studied area, respectively. In terms of total soil carbon stocks, the geo-environments of the sandy complex of Campinaranas and associations stand out, with 9450.9 Gg C. The great extension and representativeness of the sandy areas of Campinaranas characterize PARNA Virua Park as an important conservation unit for protecting Amazonian sandy soil systems. The areas under the domain of 'Espodossolos' possess the largest stocks of organic carbon and the sandy areas of Campinaranas and associations represent the most relevant geo-environment in terms of Park protecting environmental services and conservation of carbon in soils.

14 citations


Journal ArticleDOI
TL;DR: Results from multimillion fully atomistic molecular dynamics simulations of the formation of carbon nanotube S-like shaped nanostructures validates the general features of the "falling spaghetti model" proposed to explain their formation.
Abstract: Recently, Geblinger et al. [Nat. Nanotechnol. 3, 195 (2008)] reported the experimental realization of carbon nanotube S-like shaped nanostructures, the so-called carbon nanotube serpentines. We report here results from multimillion fully atomistic molecular dynamics simulations of their formation. We consider one-� m-long carbon nanotubes placed on stepped substrates with and without a catalyst nanoparticle on the top free end of the tube. A force is applied to the upper part of the tube during a short period of time and turned off; then the system is set free to evolve in time. Our results show that these conditions are sufficient to form robust serpentines and validates the general features of the ‘‘falling spaghetti model’’ proposed to explain their formation.

13 citations


DOI
02 Jul 2013
TL;DR: In this paper, the authors avaliar a adubacao nitrogenada sobre a producao, qualidade dos frutos and nitrogenio foliar de maracujazeiro-amarelo.
Abstract: Objetivou-se avaliar a adubacao nitrogenada sobre a producao, qualidade dos frutos e nitrogenio foliar de maracujazeiro-amarelo. O experimento foi realizado no Câmpus da Universidade Estadual de Mato Grosso do Sul – Aquidauana. O delineamento experimental utilizado foi o inteiramente casualizado, em parcelas subdivididas. As parcelas corresponderam as doses de N (0, 70, 140 e 210 kg ha -1 ano -1 de N), enquanto nas subparcelas, os meses de colheita (1; 2; 3; 4; 5 e 6 meses). As variaveis estudadas foram produtividade (PROD) (t ha -1 ); numero de frutos por planta (NFP); numero total de frutos (NTF); numero de frutos para consumo in natura (NFN) e numero de frutos para o consumo industrial (NFI), por hectare; massa (MF), comprimento (CF) e diâmetro dos frutos (DF); espessura da casca (ESC); rendimento de polpa (REP) e suco (RES); concentracao de solidos soluveis (SS); acidez titulavel (AT); e relacao SS/AT; e teores de N foliar (Nfol), no primeiro ano de cultivo. A producao concentrou-se principalmente no quarto mes (junho), o incremento de N no solo influenciou na massa media do fruto (175,7 g), notadamente com a adicao de 86 kg ha -1 de N; o comprimento dos frutos e os teores de N foliar aumentaram linearmente, ate 91,6 mm e 40,49 g kg -1 , respectivamente. Considerando a qualidade do fruto, na primeira safra de maracujazeiro-amarelo, nas condicoes de Aquidauana, recomendam-se 86 kg ha -1 ano -1 de N.

10 citations


Journal ArticleDOI
03 May 2013
TL;DR: In this paper, a trabalho revisar os estudos feitos for quantificar as emissoes de GEE provenientes das alteracoes do uso da terra and incendios florestais, indicando fontes e sumidouros, alem de contextualizar o estado de Roraima no cenario amazonico das mudancas climaticas.
Abstract: Emissoes de gases do efeito estufa (GEE) em Roraima – Brasil estao relacionadas diretamente a ocupacao humana e as alteracoes do uso do solo nos sistemas florestais Caracteristicas geoeconomicas e politicas foram as bases do fomento e da sedimentacao de areas de colonizacao para pequenos produtores rurais e grandes projetos de desenvolvimento regional em Roraima desde o final da decada de 1970 Isso incrementou a demanda por terras e intensificou o desmatamento por toda a regiao florestal situada ao longo dos principais eixos rodoviarios (BRs 174 e 210) Este modelo de desenvolvimento implicou na emissao de grandes somas de GEE para a atmosfera, alem de aumentar a frequencia de incendios florestais nos principais eixos de assentamento humano Objetivou-se com este trabalho revisar os estudos feitos para quantificar as emissoes de GEE provenientes das alteracoes do uso da terra e incendios florestais, indicando fontes e sumidouros, alem de contextualizar o estado de Roraima no cenario amazonico das mudancas climaticas O entendimento desta dinâmica e uma das bases do planejamento estrategico para alteracao das atuais politicas publicas locais, invertendo a logica de valoracao dos usos nao sustentaveis da terra em detrimento dos servicos ambientais provenientes da floresta

Journal ArticleDOI
TL;DR: Fungicides did not have significant effect on Bradyrhizobium survival, plant nodulation, and grain yield, which was, in average, higher than 1,200 kg ha-1.5 tonnes at harvest.
Abstract: O objetivo deste trabalho foi avaliar a compatibilidade do tratamento de sementes com fungicidas e a inoculacao com estirpes de Bradyrhizobium em feijao-caupi. Em laboratorio, avaliou-se a sobrevivencia de celulas nas sementes da cultivar BRS Guariba, tratadas ou nao com fungicidas (fludioxonil, carbendazim, carbendazim + thiram e carboxin + thiram) e inoculadas ou nao com Bradyrhizobium (estirpes UFLA3-84, BR 3267, INPA3-11B e BR 3262). Em casa de vegetacao, conduziu-se experimento em vasos de Leonard, com os mesmos tratamentos. Foram avaliados: massa de materia seca da parte aerea, alem de numero e massa de nodulos 25 dias apos a emergencia das plantas. No campo, dois experimentos foram conduzidos, tendo-se utilizado a estirpe BR 3262, com aplicacao de fungicidas nas sementes: um em area de primeiro cultivo e outro em area cultivada anteriormente com culturas anuais. Avaliaram-se, aos 35 dias, o numero de nodulos, a massa de nodulos secos e a massa de materia seca da parte aerea, e, na colheita, a produtividade de graos. Os fungicidas nao tiveram efeito significativo sobre a sobrevivencia de Bradyrhizobium, a nodulacao das plantas e o rendimento de graos, que, em media, foi superior a 1.200 kg ha-1. O tratamento de sementes de feijao-caupi com fungicidas e compativel com a inoculacao das estirpes avaliadas.

Journal ArticleDOI
TL;DR: It was concluded that soybean cultivation increases the density of rhizobial in the cerrado soil; however, this density is drastically reduced, during the dry season, by 99% at the end of the dry period.
Abstract: The biological nitrogen fixation in legumes is performed by a group of bacteria known as rhizobia. The survival of these bacteria in soils is affected by several factors, such as temperature, drought and soil fertility. This study was performed to evaluate the dynamics of rhizobia in the soil after soybean cultivation and during a dry season in the cerrado of Roraima. Three areas were sampled: i) native cerrado as reference; ii) an area previously cultivated with soybean for one season; and iii) another one cultivated for two seasons also with soybean. The soil was sampled at a depth of 0-10 cm in five times (0, 45, 90, 135 and 180 days) during the dry season (September 2006 to March 2007). The rhizobial density in the soil was evaluated by the most probable number method with infection of soybean and cowpea plants. It was observed very low number of soybean nodulating bacteria in the reference area, but a high density, of up to several hundred rhizobia capable to nodulate cowpea was measured in this same area. Cropping of soybean with inoculated seeds increased rhizobial density evaluated by both trapping hosts. In cropped areas, an intense reduction of rhizobium density was observed just after soybean harvest, and this reduction continued until the end of the period of evaluation. It was concluded that soybean cultivation increases the density of rhizobial in the cerrado soil; however, this density is drastically reduced, during the dry season, by 99% at the end of the dry period.


01 Jan 2013
TL;DR: In this article, a forest inventory was carried out in tree communities of four seasonal forest islands in the savanna of Roraima, northern Brazilian Amazon, two small (5-10 ha), one medium (10-20 ha) and one large (20-60 ha). All islands were disturbed by selective logging and fire.
Abstract: Forest islands are isolated forest fragments found in Amazonian savanna-forest transition zone of the neotropics. Information on tree communities of these formations is necessary to establish conservation policies which protect these paleoclimatic forest remnants. A forest inventory was carried out in tree communities of four seasonal forest islands in the savanna of Roraima, northern Brazilian Amazon. Two islands were defined as small (5-10 ha), one as medium (10-20 ha) and one as large (20-60 ha). All islands were disturbed by selective logging and fire. We sampled 470 individuals with diameter at Breast Height (DBH) ≥ 5 cm comprising 52 species, 41 genera and 25 families. The most species-rich families were fabaceae (11) and sapotaceae (6). Most species were pioneers (55.8%). Abarema jupunba (fabaceae) and Chrysophyllum argenteum (sapotaceae) were common in the four fragments. Greater floristic similarity was detected between the medium and large islands. Intensity and time scale of post-disturbance strongly influence tree community dynamics, and obscure a clear pattern between horizontal structure (number of individuals, DBH and basal area) and size of forest islands, although fragment size significantly affected species richness and diversity.

Journal ArticleDOI
TL;DR: In this article, the anisotropic two-dimensional nearest-neighbor Ising model with competitive interactions in both uniform longitudinal field H and transverse magnetic field Ω was studied and the thermodynamic properties as a function of temperature with values H and Ω fixed.
Abstract: We have studied the anisotropic two-dimensional nearest-neighbor Ising model with competitive interactions in both uniform longitudinal field H and transverse magnetic field Ω . Using the effective-field theory (EFT) with correlation in cluster with N = 1 spin we calculate the thermodynamic properties as a function of temperature with values H and Ω fixed. The model consists of ferromagnetic interaction J x in the x direction and antiferromagnetic interaction J y in the y direction, and it is found that for H / J y ∈ [ 0 , 2 ] the system exhibits a second-order phase transition. The thermodynamic properties are obtained for the particular case of λ = J x / J y = 1 (isotropic square lattice).

Journal ArticleDOI
31 Dec 2013
TL;DR: A densidade de plantas pode maximizar o potencial produtivo de variedades de milho melhoradas, uma vez that, em geral, estas apresentam porte mais baixo e arquitetura foliar mais ereta.
Abstract: A densidade de plantas pode maximizar o potencial produtivo de variedades de milho melhoradas, uma vez que, em geral, estas apresentam porte mais baixo e arquitetura foliar mais ereta. Objetivou-se com esse trabalho avaliar o efeito de tres densidades de plantios nos componentes de producao do milho transgenico hibrido Pioneer 30F35HR cultivado na savana de Roraima. O experimento foi conduzido na area experimental do Centro de Ciencias Agrarias da Universidade Federal de Roraima, no Campus do Cauame, no municipio de Boa Vista, Roraima, Brasil. O milho foi plantado em sistema de plantio direto. O delineamento experimental utilizado foi de blocos ao acaso com tres tratamentos e oito repeticoes. Os tratamentos consistiram de tres espacamentos entre plantas: 0,33; 0,25; e 0,20 m. As linhas de plantio foram espacadas de 0,80 m, resultando em uma populacao de 37.500, 50.000 e 62.500 plantas ha-1, respectivamente. As avaliacoes das caracteristicas morfologicas e agronomicas das plantas de milho foram feitas aos 70 e 100 dias apos o plantio. Os valores medios do numero da folha da insercao da primeira espiga, altura da insercao da primeira espiga, altura da folha bandeira, altura total da planta, numero de folhas totais, numero de folhas verdes e numero de folhas depois da primeira espiga do milho hibrido transgenico Pioneer 30F35HR nao sao influenciados pelo aumento da densidade de plantio entre 37.500 e 62.500 plantas ha-1. O aumento da densidade de plantio de 37.500 para 62.500 plantas ha-1 reduz a qualidade da espiga do milho, mas eleva a biomassa total e a produtividade de graos.

DOI
29 Oct 2013
TL;DR: A conservacao pos-colheita do maracuja-amarelo vem sendo realizada atraves de agroquimicos e refrigeracao em câmera fria, preocupando tanto sob o ponto de vista da saude alimentar quanto da geracao de onus ao produtor de baixa renda as mentioned in this paper.
Abstract: A conservacao pos-colheita do maracuja-amarelo vem sendo realizada atraves de agroquimicos e refrigeracao em câmera fria, preocupando tanto sob o ponto de vista da saude alimentar quanto da geracao de onus ao produtor de baixa renda. O objetivo deste trabalho foi avaliar o uso de tratamento hidrotermico e da solucao de cloreto de calcio na conservacao da qualidade pos--colheita de maracuja-amarelo. O delineamento experimental foi o inteiramente casualizado, em parcelas subdivididas. As parcelas foram compostas pelos tratamentos: testemunha; imersao em cloreto de calcio a 2 %; hidrotermico a 35 °C; cloreto de calcio a 2%, a 35 °C; hidrotermico + cloreto de calcio. As subparcelas foram os cinco periodos de armazenamento (0; 4; 8; 12 e 16 dias). As variaveis analisadas foram perda de massa fresca (PMF), coloracao da casca (COR), rendimentos em polpa (RP) e em suco (RS), teores de solidos soluveis (SS) e de acidez titulavel (AT), e a relacao SS/AT. Os tratamentos pos-colheita nao retardaram a senescencia nas condicoes de armazenamento adotadas. A AT e os teores de SS apresentaram reducao diaria de 0,12% e 0,14 o Brix, respectivamente, enquanto a SS/AT, PMF, RP e RS aumentaram diariamente 0,04; 2,63%; 1,09% e 0,72%, respectivamente. A utilizacao do cloreto de calcio preservou a acidez titulavel dos frutos, tendo em media 4,71 g de acido citrico por 100 g de suco. As condicoes de armazenamento adotadas no experimento possibilitam um periodo de aproximadamente 14 dias ate o completo amadurecimento dos frutos, sendo esse o provavel periodo util, a partir do qual se verificou ocorrencia de podridoes nos frutos.

Journal ArticleDOI
06 Aug 2013
TL;DR: In this article, a realidade enfrentada by estudante de graduacao da area de ciencias exatas, descrevendo uma experiencia that integrou abaco, operacoes basicas da matematica e sistemas de numeracao, with o objetivo of explorar o raciocinio logico dos estudantes e prepara-los for o estudo dos algoritmos.
Abstract: Dificuldade na aprendizagem de algoritmos e uma realidade enfrentada por estudantes de graduacao da area de ciencias exatas. O presente artigo investiga as causas do problema, descrevendo uma experiencia que integrou abaco, operacoes basicas da matematica e sistemas de numeracao com o objetivo de explorar o raciocinio logico dos estudantes e prepara-los para o estudo dos algoritmos. Foram utilizados na implementacao Visualg e Free Pascal para verificar a influencia do idioma do software na aprendizagem. O ambiente Moodle apoiou as discussoes sobre o tema e os resultados da pesquisa apontaram avancos no desenvolvimento de algoritmos e programas de computador.

Journal ArticleDOI
31 Dec 2013
TL;DR: A busca por tecnologias for producao de alimentos com alto valor agregado tem sido alvo de pesquisas nos ultimos anos as mentioned in this paper.
Abstract: A busca por tecnologias para producao de alimentos com alto valor agregado tem sido alvo de pesquisas nos ultimos anos A tecnologia de bioprocesso para producao de alimentos funcionais e um exemplo Os alimentos funcionais tem sido definidos como alimentos que, em virtude da presenca de componentes fisiologicamente ativos, fornecem beneficios a saude, alem da nutricao basica Entretanto, devido as diferentes etapas que a compoem, a tecnologia de bioprocessos para producao desses alimentos encontra-se como um dos desafios da Biotecnologia Assim, o conhecimento integrado desta tematica e imprescindivel, principalmente, quando se pretende transformar conhecimento em produto Alem disso, uma visao abrangente de areas inter-relacionadas e necessaria, para estimulo ao conhecimento, reflexoes e aplicacao pratica das ferramentas biotecnologicas existentes Objetiva-se com esse trabalho fazer uma revisao da tecnologia de bioprocessos na producao de alimentos funcionais Os mais importantes avancos sao citados e discutidos, mostrando que esta e uma das tendencias atual da biotecnologia Os alimentos funcionais, nao possuindo historico de consumo, sao enquadrados na categoria de novos alimentos Para que o produto possa ser comercializado no Brasil, e necessario que as empresas interessadas apresentem documentacao cientifica comprovando sua seguranca de uso e, ainda, que solicitem seu registro na Anvisa Estudos semelhantes devem ser conduzidos a fim de avaliar o potencial biotecnologico de outros produtos de natureza agroindustrial

Journal ArticleDOI
10 Aug 2013
TL;DR: The authors avaliou a caracteristicas fisiologicas da cana-de-acucar apos aplicacao de herbicidas em pre-emergencia.
Abstract: Objetivou-se neste trabalho avaliar as caracteristicas fisiologicas da cana-de-acucar apos aplicacao de herbicidas em pre-emergencia. Para isso, foi conduzido um experimento em esquema fatorial 2x5, onde o fator A constituiu-se das cultivares RB 867515 e SP 81-3250 , e o fator B da aplicacao em pre-emergencia do tebuthiuron, diuron, ametryn, a mistura formulada diuron + hexazinone e uma testemunha sem herbicidas. O delineamento utilizado foi inteiramente casualizado, com quatro repeticoes. As avaliacoes foram realizadas aos 90 dias apos a aplicacao dos herbicidas. A concentracao interna de carbono ( C i), a relacao carbono interno e externo ( C i /C a) e o indice SPAD das cultivares de cana-de-acucar nao foram afetadas pela aplicacao em pre-emergencia dos herbicidas. No entanto, a condutância estomatica ( gs ), a taxa respiratoria ( E ) e a taxa fotossintetica ( A ) da RB 867515 foram reduzidas quando tratadas com tebuthiuron. A A e a eficiencia no uso da agua ( EUA ) da cultivar RB 867515 foi alterada negativamente pela aplicacao do ametryn. Conclui-se que existe diferenca na sensibilidade dos genotipos de cana-de-acucar aos herbicidas, sendo que a SP 81-3250 mostrou-se mais tolerante. A aplicacao do ametryn e tebuthiuron reduz a A da RB 867515.

Journal ArticleDOI
04 Dec 2013
TL;DR: In this article, a roteiro de entrevista with perguntas semi-estruturadas was utilised to assess situacoes estressantes vivenciadas by vinte e um gestores pertencentes a duas universidades publicas do Sul do Pais.
Abstract: O estresse constitui um fenomeno complexo que necessita ser compreendido por meio de diferentes contextos. E considerado positivo e necessario para a sobrevivencia, e negativo quando sua exposicao ocorre de maneira constante e incontrolavel. O objetivo deste estudo foi analisar as situacoes estressantes vivenciadas por vinte e um gestores pertencentes a duas universidades publicas do Sul do Pais. Foi utilizado um roteiro de entrevista com perguntas semi-estruturadas. A analise dos dados foi feita por meio da construcao de categorias, a partir das verbalizacoes dos participantes. Os gestores indicaram vivenciar situacoes estressantes, demonstrando ser o estresse uma condicao inevitavel. Essas situacoes foram relacionadas a lidar com pessoas; alta demanda de trabalho; processos burocraticos; caracteristicas pessoais, entre outras. Nessas Universidades nao ha preparacao para ser gestor. Os gestores indicaram a aquisicao de experiencia profissional durante o exercicio do cargo de gestao e em cargos anteriores. Analisaram que maturidade e tempo de servico tambem auxiliam no exercicio da funcao.

Journal ArticleDOI
TL;DR: The geographical distribution of Pleistocene records of Tapirus in South America indicates that T. tarijensis was the only known species inhabiting the Tarija Valley during this time, and a taxonomic re-evaluation of Tap viruses is provided.
Abstract: Fossil remains of South American tapirs are often fragmentary and scarce compared with those of other mammals that entered South America during the “Great American Biotic Interchange”. Here, we review and add to the Pleistocene tapir remains from the Tarija Valley (Bolivia), and provide a taxonomic re-evaluation of Tapirus tarijensis. T. tarijensis was a large-sized animal, approximating the size of the living Malaysian T. indicus and the extinct North American T. haysii. The geographical distribution of Pleistocene records of Tapirus in South America indicates that T. tarijensis was the only known species inhabiting the Tarija Valley during this time.

Journal ArticleDOI
TL;DR: In this paper, the effect of delayed storage on the control of woolliness and leatheriness during cold storage of the late peach cultivars grown in Brazil was investigated, and it was shown that the delayed storage by 24 hours was effective in the controlling of physiological disorders in the white pulp cultivars.
Abstract: The study was performed to identify the effect of delayed storage on the control of woolliness and leatheriness during cold storage of the late peach cultivars grown in Brazil. The fruits were harvested at the mature-green stage. All of the cultivars were exposed to temperatures of 20 ± 0.5oC and 75 ± 3% of R.H. in a cold room for 0, 24, or 48 hours. Afterwards, the fruits were kept at 0 ± 0.5oC and 92 ± 3% of R.H. for 28 days. The yellow pulp peaches, regardless of the length of delayed storage, did not present any symptoms of woolliness or leatheriness. The white pulp peaches not submitted to delayed storage developed either one or more of the other physiological disorders. Due to their lower level of pulp firmness, the control fruits of 'Chimarrita' and 'Marli' peaches were classified as woolly fruits. The control fruits of 'Chiripa' peaches, with pulp firmness of more than 30 N, presented leatheriness. High pectinmethylesterase (PE) activity was verified in the woolly fruits. The delayed storage for 48 hours in all the cultivars provided advanced ripening. The delayed storage by 24 hours was effective in the control of physiological disorders in the white pulp cultivars.

Journal ArticleDOI
TL;DR: In this article, the authors analyzed the structure of the phytoplankton community on the nictemeral and seasonal scales and determined the influence of limnological variables.
Abstract: Reis Lake is located in the municipality of Caracarai, state of Roraima (Brazil) and is subject to fluctuations in water level. The aim of this study was to analyze the structure of the phytoplankton community on the nictemeral and seasonal scales and determined the influence of limnological variables. Sampling was performed in the rainy season (June/2006) and dry season (November/2006), considering two nictemeral cycles. The phytoplankton community was assessed with regard to composition and density, abiotic variables were analyzed simultaneously. The lake had low concentrations of oxygen, clinograde profile and water stratified during the day and homogenous at night, with low concentrations of nutrients and waters ranging from slightly acidic to alkaline. The phytoplankton was represented by 43 taxa, 35 species in the dry season and 29 species in the rainy season. Low densities of phytoplankton occurred in both nictemeral cycles, with accentuated vertical gradient. The highest densities were recorded in the dry season. Reis Lake exhibits characteristics that classify it as a polymythic and oligotrophic environment. The variability in the data was more important seasonally than on the nictemeral scale, supporting the hypothesis of the influence of the hydrological cycle on the dynamics of phytoplankton communities in floodplain lakes.

Journal ArticleDOI
31 Dec 2013
TL;DR: Verificou-se that o periodo mais favoravel para a producao de uvas vai de outubro a marco, por apresentar menores valores de pluviometria.
Abstract: A videira tem sido cultivada em diferentes regioes tropicais do Brasil. No estado de Roraima, ela foi implantada comercialmente em 2005 em Boa Vista. Ao contrario das regioes de clima temperado, as regioes tropicais apresentam condicoes termicas para a producao de uvas durante o ano inteiro. Para se avaliar as caracteristicas climaticas dos diferentes periodos do ano pode-se recorrer a diversos indices. Objetivou-se, com o presente trabalho, avaliar a aptidao climatica de Boa Vista, Roraima, para o cultivo da videira, considerando-se diferentes periodos de producao ao longo do ano. Na caracterizacao climatica, foi utilizado o Sistema de Classificacao Climatica Multicriterios Geoviticola (CCM), que e composto por tres indices: Heliotermico (IH), de Frio Noturno (IF) e de Seca (IS). Tambem foi empregado o Indice de Zuluaga (IZ), para avaliar os riscos de incidencia de doencas fungicas da videira, especialmente em relacao a incidencia de mildio (Plasmopara viticola), uma das principais doencas em regioes umidas. Com base nos indices avaliados, verificou-se que o periodo mais favoravel para a producao de uvas vai de outubro a marco, por apresentar menores valores de pluviometria. Nos outros meses, podem ser realizadas podas de formacao de ramos, sem a producao de frutos, como ja ocorre em outras localidades tropicais do Brasil.

Journal ArticleDOI
TL;DR: The highest sugar apple seedling emergence speed and growth rate were obtained when the seeds were subjected to the method of scarification and soaking in GA3 for 12-24 h, which resulted in greater economy, practicality and financial savings.
Abstract: Cultivation of sugar apple has increased in the Setentrional Amazon, but one of the problems for obtaining quality seedlings is related to overcoming dormancy of its seeds. The objective of the present study was to evaluate the efficiency of physical and chemical methods to break sugar apple seed dormancy. Ripe sugar apple fruit were collected from an orchard located in Boa Vista-RR, pulped and their seeds washed in running water and dried in the shade for 24 h. A completely randomized experimental design was used in a factorial 2 (0 and 1000 mg L–1 GA3 = gibberellic acid) × 4 immersion times (0, 6, 12 and 24 h) × 2 (with and without scarification) with 4 replications and 50 seeds per replication. The seeds were then sown in beds under greenhouse-type shade with 50% brightness in soil and sand mixture (3:1 v / v) subtrate. The following were evaluated 30 days after sowing: percentage of emergence (%) and shoot growth after seedling emergence, at four-day intervals. At fifty‑eight days after sowing, the shoot and root lengths, number of leaves, shoot and root dry matter were assessed. The highest sugar apple seedling emergence speed and growth rate were obtained when the seeds were subjected to the method of scarification and soaking in GA3 for 12-24 h. Scarification and soaking in water for 24 h resulted in greater economy, practicality and financial savings.

01 Jan 2013
TL;DR: In this article, the authors present the internationalization of a country taking for granted the identification of multiple layers of development of international relations processed through diplomatic and paradiplomatic actions, and consider the characterization of a multiplicity of decentralized and parallel actions in comparison to the political agenda of the foreign ministries that also have been embodied by the consolidation of new profiles of diplomacy.
Abstract: This article presents the internationalization of a country taking for granted the identification of multiple layers of development of international relations processed through diplomatic and paradiplomatic actions. This piece of writing considers the characterization of a multiplicity of decentralized and parallel actions in comparison to the political agenda of the foreign ministries that also have been embodied by the consolidation of new profiles of diplomacy. Throughout this discussion subsidies are provided in order to have an apprehension about the diplomatic and paradiplomatic actions with reference to the impact on the foreign policy lato sensu.

Journal Article
TL;DR: A trabalho realizado at the Universidade Federal da Paraiba, em Areia-PB, no periodo de fevereiro a dezembro de 2010 as discussed by the authors avaliado a massa media of tuberas comerciais, a produtividade comercial de tuberas, a percentagem de tubera classificadas como primeira, o teor de potassio nas folhas and a dose de maxima eficiencia economica.
Abstract: O trabalho teve como objetivo avaliar a influencia de doses de potassio sobre o rendimento do inhame (Dioscorea cayennensis) e determinar sua dose economica para a produtividade de tuberas comerciais. O experimento foi realizado na Universidade Federal da Paraiba, em Areia-PB, no periodo de fevereiro a dezembro de 2010. O delineamento experimental utilizado foi de blocos casualizados completos, com seis tratamentos compostos pelas doses de 0; 50; 100; 150; 200 e 250 kg ha-1 de potassio, em quatro repeticoes. Foram avaliados a massa media de tuberas comerciais, a produtividade comercial de tuberas, a percentagem de tuberas classificadas como primeira, o teor de potassio nas folhas e a dose de maxima eficiencia economica. A maxima massa media de tuberas comerciais foi de 2,60 kg, obtida na dose de 126 kg ha-1 de potassio. A dose de 189 kg ha-1 de potassio foi responsavel pela maxima produtividade comercial de 17,7 t ha-1 de tuberas. A maxima percentagem de tuberas classificadas como de primeira foi de 88%, alcancada na dose de 171 kg ha-1 de potassio. O teor maximo de potassio nas folhas de inhame foi de 22,3 g kg-1 obtido na dose de 155 kg ha-1 de potassio e a dose de maxima eficiencia economica de potassio para a produtividade comercial de tuberas foi de184 kg ha-1.

Journal ArticleDOI
02 May 2013
TL;DR: The non-indifference as a belief-idea would support Brazilian-Guyanese historical relations, explaining why Brazil approached a country considered by many as low political and economic relevance in South America, but that has gained importance into the Brazilian reading on regional integration as discussed by the authors.
Abstract: Brazil's ties with its South American neighbours have been marked by a hybrid of cordiality and cooperation on the one hand, and responsibility and pragmatism on the other. Thus, the relationship between Brazil and Guyana seeks to generate prosperity and cohesion in South America, while aimed at promoting regional development in the Amazon. The aim of this paper is to understand the "non-indifference" as a principle of Brazilian South American policy and a road map of international relations of Brazil in its neighbourhood and surroundings. The non-indifference, as a belief-idea, would support Brazilian-Guyanese historical relations, explaining why Brazil approached a country considered by many as low political and economic relevance in South America, but that has gained importance into the Brazilian reading on regional integration.