ANÁLISE NÃO LINEAR DA INFLUÊNCIA DA FISSURAÇÃO NA RESISTÊNCIA AO ARRANCAMENTO DE PINOS EMBUTIDOS EM CONCRETO

Quando conectores de aço com cabeça são solicitados à tração, uma forma de ruptura é ocasionada pelo destacamento de uma região de concreto em torno do conector, em formato de cone. Sabe-se que o aumento do grau de fissuração na região do cone influencia negativamente na resistência do conjunto. Este trabalho apresenta uma modelagem computacional com base em uma série de ensaios experimentais caracterizados pelo arrancamento de conectores de aço embutidos em prismas bi-apoiados de concreto armado. A modelagem visou avaliar a influência do grau de fissuração na resistência do conjunto, onde variou-se a taxa de armadura de flexão de 0,3 até 3,2% entre os modelos, resultando em diferentes graus de fissuração. A análise numérica foi realizada usando o software MIDAS FEA. Foi feito um estudo paramétrico em um dos modelos, para ajustar as propriedades do concreto, sendo os alvos do estudo a resistência à tração, o módulo de elasticidade e a energia de fratura. Os valores definidos na análise foram extrapolados para os outros modelos. Foram determinadas cargas de ruptura e gráficos de carga x deslocamento para os modelos numéricos. Tais resultados foram comparados com os resultados experimentais, apresentando boa correlação, v dos modelos computacionais

Apical transportation associated with ProTaper® Universal F1, F2 and F3 instruments in curved canals prepared by undergraduate students

Objective: This study evaluated apical transportation associated with ProTaper® Universal F1, F2 and F3 rotary files in curved canals prepared by undergraduate students. Material and Methods: Twenty mesial roots of mandibular molars with curvatures ranging between 25° and 35° were selected. Mesiobuccal canals were instrumented by twenty students with the ProTaper® system (Dentsply-Maillefer, Ballaigues, Switzerland) according to the manufacturer’s instructions. Pre-flaring was performed with S1 and SX files. A #15 K-file was inserted into the root canal up to the working length (WL), and an initial digital radiograph was taken in a buccolingual direction (baseline). Afterwards, the S1, S2, F1, F2, and F3 files were employed up to the WL. Other radiographies were taken in the same orientation of the baseline after the use of the F1, F2, and F3 files, with each file inserted into the root canal. The radiographic images were overlapped, and the Image J software was used to measure the distance between the rotary files’ ends and the #15 K-file’s end, characterizing the apical transportation. Data were analyzed by Repeated Measure ANOVA and by the SNK post hoc test (P<0.05). Results: It was verified that file size affected apical transportation significantly (P<0.001). The F3 file showed higher apical transportation than F1 and F2, while between these last files there was no difference. Conclusion: The undergraduate students produced lower apical transportation in curved canals when they did not use the F3 rotary file

American oil palm from Brazil: genetic diversity, population structure, and core collection.

The American oil palm [Elaeis oleifera (Knuth) Cortés] has pronounced importance in oil palm breeding programs. Here, a germplasm bank (GB) of E. oleifera plants collected in the Amazon rainforest in Brazil was submitted to single nucleotide polymorphism (SNP) marker identification, selection, and use, aiming to characterize genetic diversity and population structure and to design a core collection (CC). Five hundred and fifty-three plants from 206 subsamples, collected at 19 localities spread throughout six geographic regions, were submitted to genotyping-by-sequencing analysis. A set of 1,827 high-quality SNP markers was then selected and used to run the genetic diversity and population structure analysis. The genetic diversity found is of moderate degree, and probably only a small portion of the species diversity is represented in the collection. The possible reason for that is the collecting strategy used, which collected subsamples only around the most prominent watercourses in the region. The average degree of genetic differentiation among subsamples is very high, indicating the presence of high interpopulation differentiation. The collection showed a low level of endogamy. The low average gene flow found indicates that genetic isolation caused by drift is occurring, and there is a need to review the conservation strategy. A set of 245 SNPs distributed throughout all 16 chromosomes was used to design CC based on maximizing the strategy of diversity. The optimal adjustment of the validated parameters, maintained while taking fewest subsamples, led to the choice of a model containing 20% of the entire collection as the ideal to form the CC

Protein requirement of tambaqui juveniles (Colossoma macropomum) after feed deprivation

The aim of this work was evaluate protein requirement of tambaqui (Colossoma macropomum) juveniles after feed deprivation. During 60 days, fish (50,3 ± 0,26 g) were fed on four isoenergetics diets with different protein content (28, 32, 36 and 40% crude protein) at two feeding regimes (with and without feed deprivation) under completely random factorial design (4x2) in triplicate. Water quality parameters and performance index were evaluated at 1º, 15º and 60º days. Water quality parameters were kept at normal fish cultivation patterns. No mortality in the tested treatments. There were observed differences among treatments for performance indexes analyzed: growth rate, feed efficiency, daily feed consumption, crude protein consumption, efficiency protein rate and relative weight gain, except for hepatosomatic index. Hyperfagia was detected indicating the occurrence of compensatory growth. Fat content and body protein deposition increased in fishes refed on 36% of crude protein. These results explain some data observed belong the experiment like the increase of weight gain, of the hyperfagia time extension, of the growth rate and of the feed efficiency. Therefore those fish shows increase on weight gain, hyperfagia time, growth rate and feed efficiency. There is no influence of feed deprivation on protein requirement tambaqui juveniles.O objetivo deste trabalho foi avaliar a exigência protéica de juvenis de tambaqui (Colossoma macropomum) após a privação alimentar. Os peixes (50,3 ± 0,26g) foram submetidos a quatro rações isoenergéticas com diferentes concentrações protéicas (28, 32, 36 e 40% proteína bruta) e dois regimes alimentares (com privação e sem privação) durante 60 dias. O delineamento experimental foi inteiramente casualizado, em esquema fatorial 4x2, em triplicata. Avaliaram-se os parâmetros de qualidade de água e de desempenho no 1º, 15º e 60º dia de experimento. Os parâmetros da qualidade da água permaneceram dentro dos padrões de cultivo. Não houve mortalidade nos tratamentos testados. Foram observados diferenças entre os tratamentos para os índices de desempenho analisadostaxa de crescimento específico, eficiência alimentar, consumo diário de ração, consumo de proteína bruta, taxa de eficiência protéica e ganho de peso relativo, com exceção do índice hepatossomático. Houve hiperfagia, indicando a existência de crescimento compensatório. Os peixes realimentados com 36% proteína bruta tiveram incremento no teor de gordura visceral e maior deposição de proteína corporal. Estes resultados explicam uma melhora nos dados de ganho de peso, duração da hiperfagia, taxa de crescimento e eficiência alimentar. A privação alimentar não influencia a exigência protéica em juvenis de tambaqui