951 resultados para Artificial aging and KNO3


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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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A produtividade da soja, no sistema de semeadura direta (SSD), pode ser influenciada pelo tipo de cobertura vegetal que antecede, bem como pela calagem superficial. Todavia, os efeitos dessa técnica sobre os componentes da produção e sobre a qualidade fisiológica das sementes têm sido pouco estudados, principalmente para a soja safrinha sob SPD. Assim, objetivou-se avaliar algumas características agronômicas, os componentes da produção, a produtividade e a qualidade fisiológica da semente da soja cultivada na safrinha, em função de diferentes coberturas vegetais, com e sem calagem superficial, sob SSD. O experimento foi conduzido no ano de 1999/00, na Fazenda Experimental Lageado, FCA/UNESP/Botucatu-SP. O delineamento experimental foi o de blocos casualizados em parcela subdividida, com 4 repetições. As parcelas de 6m x 10m, foram constituídas de sorgo de Guiné vermelho e branco (Sorghum bicolor), milheto (Pennisetum americanum), painço (Panicum dichotomiflorum), vegetação espontânea e sem vegetação. Aos 53 dias após a emergência, as coberturas vegetais foram dessecadas e acamadas, seguindo-se a aplicação superficial de 3,1 t.ha-1 de calcário na metade das parcelas, visando à elevação da V%=70%. Após 2 semanas, realizou-se a semeadura da soja, cv. IAC-19, em safrinha. Determinou-se o estande final, a altura de inserção da primeira vagem, a altura de planta, o número total de vagens e vagens chochas por planta, o número de sementes por vagem total, a massa de 100 sementes e a produtividade. Com relação à qualidade fisiológica das sementes determinou-se a germinação e o vigor, por meio dos testes de envelhecimento artificial, germinação a temperatura subótima, M.S. de plântula e condutividade elétrica. Na implantação do SSD, a cobertura vegetal e a calagem superficial não afetam as características agronômicas, os componentes da produção, a produtividade de sementes e a qualidade fisiológica das sementes de soja cultivadas em safrinha, com exceção da condutividade elétrica.

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The occurrence of Aeromonas spp., Vibrio cholerae, and Plesiomonas shigelloides in fresh water from various sources in Araraquara, State of São Paulo, Brazil was determined. Samples from ten distinct irrigation systems used in vegetable cultivation, from five distinct streams, from two reservoirs, from one artificial lake, and from three distinct springs were analyzed. All isolates were serotyped and tested for hemolysin, cytotoxin, heat-stable (ST) and heat-labile (LT) enterotoxins production; presence of plasmid; autoagglutination and drug resistance. V. cholerae isolates were also tested for cholera enterotoxin (CT) production, and Aeromonas isolates for suicide phenomenon. No P. shigelloides was found. V. cholerae non 01 was found in five irrigation water samples and in three stream samples. Aeromonas sp. were isolated in two samples of irrigation water, in three streams, and in one reservoir. All the V. cholerae and Aeromonas isolates were positive for P-hemolysin production, and all Aeromonas isolates were positive for suicide phenomenon; cytotoxic activities were observed in two Aeromonas strains. Cholera enterotoxin was not found in eight V. cholerae non-01 isolates tested by the Y-1 mouse adrenal cell. All isolates were also negative for the other virulence markers. Ii cholelerae isolates were found to be sensitive to the majority of drugs tested, while Aeromonas strains presented multiple drug resistance..

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This paper presents an efficient neural network for solving constrained nonlinear optimization problems. More specifically, a two-stage neural network architecture is developed and its internal parameters are computed using the valid-subspace technique. The main advantage of the developed network is that it treats optimization and constraint terms in different stages with no interference with each other. Moreover, the proposed approach does not require specification of penalty or weighting parameters for its initialization.

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This study was aimed at assessing the changes in sperm motion patterns and the percentage of acrosome reaction (AR) in domestic cat semen after treatment with either ionomycin or progesterone (P(4)). Ten ejaculates were collected from five tomcats using an artificial vagina, and were diluted, centrifuged and resuspended in a capacitation medium. Samples were evaluated and divided into seven equal aliquots and, after 2 h at 25 degrees C, were incubated for 30 min at 38 degrees C in 5% CO(2) and then analyzed. Computer-assisted sperm analysis and a combination of three fluorescent probes were used to assess sperm plasma, acrosomal membrane integrity and mitochondrial transmembrane potential. Thirty minutes after the start of incubation, P(4) was added (10 mu g/ml) to the P1 group. Groups P2 and P3 were supplemented with P(4) (10 and 20 mu g/ml, respectively) only after 2 h of incubation, and groups I1 and I2 were supplemented with ionomycin (4 and 8 mu M, respectively) 2 h after incubation. Group E was supplemented with ethanol (0.6%) at 2 h after incubation and group C received no supplementation. Ionomycin and P(4) treatments led to a hyperactivation-like sperm motion and an increase (p < 0.05) in the percentage of AR. Although a higher (p < 0.05) percentage of AR was obtained in group I2 when compared with all P(4) groups, a decrease (p < 0.05) in total and progressive motility was observed in I2 group. As I1 group was similar to I2 to induce AR without diminishing sperm motility, we can conclude that ionomycin at 4 mu M seems to be more suitable to trigger AR in domestic cat sperm.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Purpose: The purpose of this study was to assess, through electromyographic activity (EMG), the silent period (SP) of masseter and anterior temporal muscles in dentate subjects (DS) and complete denture wearers (CDW).Materials and Methods: The evaluations were performed at the initial and final period of the mastication for the DS group. For the CDW group, the evaluations were performed at the initial period of mastication, with old complete dentures worn for more than 10 years (OCDW) and at the final period of the mastication with new complete dentures (NCDW), 5 months after rehabilitation. Twenty-four asymptomatic subjects (12 DS, 12 CDW) answered a questionnaire based on the Research Diagnostic Criteria for temporomandibular disorders. The CDW group answered the questionnaire before and after new denture insertion and after 5 months of rehabilitation. The SP of the muscles was recorded through EMG at the initial and final periods of mastication using artificial food (Optocal). The operator monitored 35 chewing cycles performed to grind the artificial food and selected eight open-close-clench-chewing cycles for the record.Results: The SP of the muscles analyzed with new complete dentures showed no statistical difference in comparison to the old dentures. There was a statistically significant difference in the SP between the CDW and DS groups for initial and final chewing.Conclusion: Lowered muscular capacity and ability reduced the SP of muscles after rehabilitation with NCDWs.

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Because of the growing concerns regarding fluoride ingestion by young children and dental fluorosis, it is necessary to develop new dentifrices. Objective: The aim of this study was to evaluate the effect of dentifrices with calcium citrate (Cacit) and sodium trimetaphosphate (TMP) on enamel demineralization. Material and Methods: Enamel blocks (n=70), previously selected through surface hardness analysis, were submitted to daily treatment with dentifrices diluted in artificial saliva and to a pH-cycling model. The fluoride concentration in dentifrices was 0, 250, 450, 550, 1,000 and 1,100 mu g F/g. Crest (TM) was used as a positive control (1,100 mu g F/g). Cacit (0.25%) and TMP (0.25%) were added to dentifrices with 450 and 1,000 mu g F/g. Surface hardness was measured again and integrated loss of subsurface hardness and fluoride concentration in enamel were calculated. Parametric and correlation tests were used to determine difference (p<0.05) and dose-response relationship between treatments. Results: The addition of Cacit and TMP did not provide a higher fluoride concentration in enamel, however it reduced (p<0.05) mineral loss when compared to other dentifrices; the dentifrice with Cacit and TMP and a low fluoride concentration presented similar results when compared to a dentifrice with 1,100 mu g F/g (p>0.05). Conclusions: Dentifrices with 450 and 1,000 mu g F/g, Cacit and TMP were as effective as a gold standard one.

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The comparative study of the ultrastructure of the midgut epithelium of stingless bee larvae that eat plant protein (pollen) and animal protein (carrion) throughout the larval phase, shows variations in the digestive cells that are only relative to larval aging and not to the type of larval diet. The cells of older larvae present a cytoplasm with empty spaces that result from emptying of lipid and glycogen stocks, and the presence of autophagic vacuoles. These results are discussed in relation to the hypothesis that variations in the digestive tract of insects may be associated with different diets or phylogeny. We conclude that different diets do not determine cell morphology adaptations in the studied species. As the variations in the ultrastructure of the midgut epithelium are the same in all studied species, including the necrophagous species Trigona hypogea, throughout the larval stage, this sequence of changes seems to be due to different physiological state during larval development.