1,381 research outputs found

    A finite element model using a unified formulation for the analysis of viscoelastic sandwich laminates

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    In this paper we present a layerwise finite element model for the analysis of sandwich laminated plates with a viscoelastic core and laminated anisotropic face layers. The stiffness and mass matrices of the element are obtained by Carrera's Unified Formulation (CUF). The dynamic problem is solved in the frequency domain with viscoelastic frequency-dependent material properties for the core. The dynamic behaviour of the model is compared with solutions found in the literature, including experimental data

    Ação do Agrostemin sobre a altura e o número de folhas de plantas de soja (Glycine max L. MERRILL cv. IAC-8)

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    A greenhouse experiment was conducted to evaluate the effects of Agrostemmin (plant stimulant) on height and number of leaves of soybean plants (Glycine max L Merril cv. IAC-8). Six treatments were studied: check (T1); 0,125g Agrostemmin/l00g seed (T2); 0,125g Agrostemmin/100 seed and foliar spraying 333 ppm (T3); 0,125g Agrostemmin/l00g seed and foliar spraying 500 ppm (T4); foliar spraying 333 ppm (T5) and foliar spraying 500 ppm (T6). Three samplings were made at 14 day intervals. The experimental layout was completely randomized, using two variance, testing regression effects. Agrostemmin applied to the seed (T2) or sprayed on the leaves at the rate of 500 ppm (T6) increased height and number of leaves of soybean, whereas the combination of Agrostemmin applied to the seeds and sprayed at 500 ppm (T4) decreased those values.O presente estudo teve por finalidade avaliar o efeito de um estimulante vegetal, o Agrostemin, sobre a altura e o número de folhas das plantas de soja (Glycine max L. MERRILL cv. IAC-8). O experimento foi conduzido em casa de vegetação. Foram estudados seis tratamentos, correspondentes as seguintes dosagens, épocas e formas de aplicação: testemunha (T1); 0,125g Agrostemin/l00g sementes (T2); 0,125g Agrostemin/100g semente e pulverização foliar à 333 ppm (T3); 0,125g Agrostemin/l00g sementes e pulverização foliar à 500 ppm (T4); pulverização foliar à 333 ppm (T5) e pulverização foliar à 500 ppm (T6). Realizaram-se três coletas de plantas, com intervalo de 14 dias. O experimento foi em delineamento inteiramente casualizado, utilizando-se duas análises de variância com desdobramento em efeitos de regressão. Através dos resultados obtidos concluiu-se que o Agrostemin quando aplicado via semente (T2) ou via foliar à 500 ppm (T6), aumentou a altura e o número de folhas. Ao aplicar o produto via semente mais via foliar à 500 ppm (T4), estas medidas diminuiram

    Allelopathic Interactions Among Forage Grasses and Legumes

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    Aqueous extracts at 10% were prepared with the shoots of the grasses Brachiaria brizantha cv. Marandú, B. decumbens, B. humidicola, and of the legumes Calopogonium mucunoides, Leucaena leucocephala, Stylosanthes guianensis cv. Mineirão. The effects of the extracts were evaluated on the germination and on the radicleelongation of the forages. The pH, the electric conductivity and the osmotic potential of the extracts were determined. The germination and radicle biossays were conducted in germination chambers, with controlled temperature and photoperiod. The pH and the presence of ions did not contribute to the effects observed. The extracts of the legumes tended to reduce the growth of the grasses to a greater extent than the grasses reduced the growth of the legumes. The radicle-elongation was a more sensitive indicator to evaluate the effects of the extracts than the germination (%). The C. mucunoides was the legume with higher allelopathic effect, while among the grasses there was not a remarkable species

    Physiological and Chemical Characteristics of Five Cultivars of Cynodon

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    The experiment was carried out at UNESP, Brazil, to evaluate five Cynodon cultivars: (Cynodon nlemfuensis Vanderyst cv “Tifton 68”, Cynodon spp. cv “Tifton 85”, Cynodon dactylon cv “Florakirk”, Cynodon nlemfuensis Vanderyst var. nlemfuensis cv “Florico” e Cynodon nlemfuensis Vanderyst var. nlemfuensis cv “Florona”). Plants were sampled once a week from 14 to 84 days of growth to study physiological characteristics and at 14-day intervals to study chemical characteristics. The following variables were studied: DM production, leaf/stem ratio, leaf weight/total dry matter ratio, relative growth rate, chlorophyll contents, leaf area, specific leaf area, LAI, and the contents of CP, NDF, and ADF. The five cultivars showed similar responses for all variables studied. The data obtained allowed us to conclude that the five cultivars would be better managed when cut or grazed at 28-42 days intervals of plant growth

    Influence of etylen on the chemical characteristics of mango fruits var. Keitt, harvested in the pre-climateric stage

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    Frutos de manga (Mangifera indica L.) variedade Keitt, colhidos em estádio pré-climatérico, receberam tratamento com 500 e 1.000 ppm de Ethrel (com exceção da testemunha), sendo submetidos a determinações de carboidratos solúveis, vitamina C, proteínas e umidade, de acordo com amostragens realizadas 3, 6, 9 e 16 dias pós-colheita. Os resultados obtidos, revelaram que o Ethrel não excerceu nenhuma influência nas características químicas dos frutos e que, somente em termos de carboidratos solúveis e vitamina C, os frutos mostraram alterações durante a maturação.Mango fruits (Mangtfera indica L.) Keitt variety, harvested in the pre-climateric stage were treated with 500 and 1,000 ppm of Ethrel (except the control). Soluble carbohydrates, vitamin C, proteins and humidity were evaluated on the samples at 3, 6, 9 and 16 days post-harvest. The results obtained, showed that Ethrel did not have influence on the chemical characteristics of the fruits. Fruits showed modificátions during the maturation only for the parameters of soluble carbohydrate and vitamin C

    Efeitos de potenciais de água no solo, em diferentes estádios fenológicos da cultura da cevada (Hordeum vulgare L.)

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    Objetivando avaliar os efeitos de défices hídricos, em três estádios fonológicos da cultura da cevada (Hordeum vulgare L.), foi conduzido experimento em vasos, com delineamento em blocos ao acaso. Foram utilizados nove tratamentos decorrentes da combinação dos potenciais mínimos de água no solo de -0,05, -0,20 e -1,50 MPa, com os estádios fenológicos de máximo perfilhamento, florescimento e grão leitoso, permanecendo uniformizados durante o restante do ciclo, entre os potenciais de -0,01 a -0,05 MPa. Os resultados de produção, peso e teor de proteína dos grãos, tamanho de espigas, número total e número de espigas chochas, mostraram que os efeitos de défices hídricos variaram com a intensidade, duração e estádio fenológico da cultura, onde o estádio de florescimento mostrou-se mais sensível ao défice de água. A ocorrência de défice hídrico intenso, em cada um dos estádios, bem como ciclos repetidos de défices moderados ou intensos, levaram à diminuições significativas na produção de grãos, além de ocorrer tendência ao aumento do teor de protema dos grãos. O manejo da irrigação na cultura da cevada, quando se busca a máxima eficiência no uso da água, deve levar em conta os diferentes estádios fenológicos.The experiment was carried out under greenhouse conditions, with the objective of evaluating the effects of water deficits in three phenological phases of barley crop (Hordeum vulgare L.). Pots were arranged in a randomized block design with nine treatments. They originated from the combination of minimum soil water potentials of -0,05, -0,20 and -1,50 MPa, with the phenological phases of maximum tillering, flowering and milky grain, having been hold uniformly along the rest of the cycle, between -0,01 and -0,05 MPa potentials. Weight of grain, protein content, spike sizes, spike total number and number of hollow spikes, showed that water deficit effects varied with the intensity, duration and phenological phase of the crop, where the flowering phase showed to be most sensitive to the water deficit. Ocurrence of intense water deficit in each phase, as well as repeated cycles of moderated or intense water deficits, led to significative reductions in grain production. Besides, a tendency to a higher grain protein content was observed. Irrigation manegement of barley crop, aiming to a maximum efficience in water consumption must take into account lhe different phenological phases

    Reguladores Vegetais E Sombreamento Na Emergência De Plântulas De Macadâmia

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    This study aimed to evaluate the effect of plant growth regulators and shading on seed germination of macadamia nut trees. The experiment was conducted in a seedling production nursery of the company "QueenNut Macadâmia" located in the "Palmeiras" Farm, Dois Córregos, São Paulo (SP) state, Brazil. The Treatments were T1: water (control) under a shading screen, T2: GA4+7 + N-(phenylmethyl)-aminopurine (Promalin®) at 200 mL L-1 under a shading screen, T3: Promalin® at 400 mL L-1 under a shading screen, T4: gibberellic acid (GA3) + kinetin (Kt) + 3- indolebutyric acid (IBA) - Stimulate® at 5 mL kg-1 seeds under a shading screen, T5: Stimulate® at 10 mL kg-1 of seeds under a shading screen, and T6: water (control) under no shading screen. Seeds were soaked in the solutions or in water containing plant growth regulators for 24 hours. Then, they were dried and sown in sand. 450 seeds were used for each treatment. The evaluations began from seedling emergence by counting the total number of seedlings per treatment. A high average of macadamia nut tree seedling emergence was obtained in the treatments GA4+7 + N-(phenylmethyl)-aminopurine (Promalin®) 400 mL L-1 with Sombrite® (75.7%), GA4+7 + N-(phenylmethyl)-aminopurine (Promalin®) 200 mL L-1 (72.6%) Sombrite® and water (control) without Sombrite® (71.5%). © 2016, Universidade Federal de Uberlandia. All rights reserved.3251263126

    Valorisation of kraft lignin by using vanillin and lignin-based polyurethanes: Use of the biorefinery concept

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    In kraft pulp mills, the capacity of the recovery boiler is very often a limiting factor to the increase of the pulp production. Until several decades ago, an upgrade to boiler system for dealing with higher quantities of black liquor was the only alternative. The possibility of lignin extraction from black liquor seems to be much more attractive, either for energy production or combustion elsewhere, or to serve as feedstock for chemicals production. Since the beginning of the 90’s, associate Laboratory LSRE/LCM has been focused on overcoming expansion limitations in pulp industries and, in this work, we show an alternative to this industry segment for the utilization of lignin and producing high added value chemicals from renewable biomass materials. Based on the biorefinery concepts, an integrated process for producing vanillin from kraft lignin oxidation has been proposed and each of the needed unit operations has been investigated to provide a deeper scientific understanding on this subject.FCT - projects POCTI/EQU/33198/99, POCI/EQU/61738/2004 and Grant SFRH/BD/18415/2004. CYTED IV.17/2002-2006. Luso-French actions F13/06 and F32/08

    Efeitos de fitorreguladores e nitrato de potássio na germinação de sementes do limão 'volkameriano'

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    The purpose of this research was to study the effects of growth regulators and potassium nitrate on 'volkameriana' lemon seed germination. The medium for seed germination was filter paper with distilled water. The seeds were removed from ripe fruits, washed, dried and stored at 4-5°C. After this the seeds were treated with growth regulators and potassium nitrate during 24 hours. The treatments were H2O; 50 mg/lof GA3; 250 mg/lof GA3; 50 mg/lof GA4 + GA7 + phenylmethylaminepurine; 100 mg/l of GA4 + GA7 + phenylmethyla-minepurine; 20 mg/lof phenylmethylaminepurine; 40 mg/lof phenylmethylaminepurine and 0,2% of KNO3. The evaluations were performed every two days, starting 15 days after seeding. The moisture with GA4 + GA7 plus phenylmethylaminepurine at 50 mg/lproved to be the most beneficial in enhancing seed germination.Foram estudados os efeitos de substâncias reguladoras de crescimento, bem como do nitrato de potássio (KNO3), na germinação de sementes do limão 'volkameriano' (Citrus volkameriana Pasq.). O experimento foi realizado em germinador, contendo papel de filtro umedecido com água destilada e gerbox, como meio para a germinação das sementes. Estas foram retiradas de frutas maduras, lavadas, secas à sombra e armazenadas durante 101 dias em câmara fria. Logo após, foram tratadas com os fitorreguladores e o KNO3 por 24 horas, conforme os tratamentos: H2O; 50 mg/l de GA3; 250 mg/l de GA3; 50 mg/l de GA4 + GA7 + fenilmetilaminopurina; 100 mg/l de GA4 + GA7 + fenilmetilaminopurina; 20 mg/lde fenilmetilaminopurina; 40 mg/lde fenilmetilaminopurina e 0,2% de KNO3. As avaliações foram realizadas depois de 15 dias da semeadura, sendo o intervalo de 2 dias. Através da análise estatística dos resultados obtidos, foi possível concluir que no tratamento com 50 mg/lde GA4 + GA7 + fenilmetilaminopurina houve a maior porcentagem de germinação (89,00%) de sementes, num menor tempo médio (22,29 dias)

    Influência de fitorreguladores e nitrato de potássio na germinação de sementes e no crescimento de porta-enxerto de Citrus amblycarpa

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    The effects of growth regulators (gibberellins and cytokmins) and potassium nitrate were evaluated for Citrus amblycarpa seed germination and rootstock growth. First an experiment was performed in a germinator, using as a medium for seed germination filter paper wetted with distiled water. Seeds were treated with growth regulators and potassium nitrate during 24 hours. The results obtained indicate that the treatment of 100 mg/1 of GA4 + GA7 + phenylmethylaminepurine was the best, with a percentage of germination of 88% at 21 days. Based on the results obtained in the germinator, seeds of Citrus amblycarpa were seeded in soil and when the seedlings were 6 cm high they were sprayed with 50 mg/1 of GA4 + GA7 + phenylmethylaminepurine; 100 mg/1 of GA4 + GA7 + phenylmethylaminepurine and 150 mg/1 of GA4 + GA7 + phenylmethylaminepurine. Dry weights of leaves and stems, leaf area and height of plants were evaluated. The analysis of these parameters showed that the GA4 + GA7 + phenylmethylaminepurine at 50 mg/1 was the best treatment.Foram avaliados os efeitos de fitorreguladores (giberelinas e citocininas) e nitrato de potássio (KNO3), na germinação de sementes e na promoção do crescimento de "seedlings" do porta-enxerto 'Nasnaran' (Citrus amblycarpa Ochese). Realizou-se primeiramente o experimento em germinador, contendo papel de filtro umedecido com água destilada e gerbox, como meio para a germinação das sementes. Os tratamentos foram realizados mediante imersão das sementes, em soluções preparadas com os fítorreguladores e KNO3, durante 24 horas. Através dos resultados obtidos, concluiu-se que o tratamento com 100 mg/1 de GA4 + GA7 + fenilmetilaminopurina, apresentou a maior porcentagem de germinação (88%), num tempo médio de 21 dias. Tomando como base o resultado do germinador, sementes de Citrus amblycarpa foram semeadas em canteiros e quando as plantas atingiram a altura de 6,0 cm receberam 2 pulverizações com 0; 50; 100 e 150 mg/1 de GA4 + GA7 + fenilmetilami-nopurina, com intervalo de 21 dias. Avaliou-se a matéria seca total, caule e folhas, área foliar e altura das plantas, sendo que a análise desses parâmetros mostrou que o GA4 + GA7 + fenilmetUaminopurina na concentração de 50 mg/1 foi o tratamento que apresentou os melhores resultados
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