321 resultados para Cotes-Plets
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A análise da interação genótipo x ambiente utilizda no melhoramento de plantas tem sofrido mudanças na última década, melhorando a sua eficiência quanto à seleção dos genótipos sob diferentes condições ambientais. O objetivo deste trabalho foi analisar a produtividade e estabilidade de 12 genótipos de arroz em oito ambientes, durante os anos 2005 e 2006, na Colômbia. O delineamento utilizado foi o de blocos ao acaso com quatro repetições. Os parâmetros de estabilidade fenotípica e o agrupamento dos ambientes foram estimados pelo estudo da interação genótipo x ambiente, segundo o método SREG (Regressão nos sítios ou locais) e seu gráfico biplot (GGE). As análises estatísticas indicaram diferenças significativas (com 5% de probabilidade de erro) entre genótipos e entre ambientes e significância (com 5% de probabilidade de erro) da interação genótipo x ambiente, sugerindo uma resposta diferente dos genótipos nos vários ambientes. No método SREG, os dois primeiros componentes principais da interação explicaram 75,29% da interação. Os genótipos 400094, 350361 e a variedade Fedearroz 50 foram considerados os de maior produtividade. Segundo o gráfico biplot GGE, os ambientes La Libertad e Escobal foram os mais favoráveis para o cultivo do arroz.
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Several statistical models can be used for assessing genotype X environment interaction (GEI) and studying genotypic stability. The objectives of this research were to show how (i) to use Bayesian methodology for computing Shukla's phenotypic stability variance and (ii) to incorporate prior information on the parameters for better estimation. Potato [Solanum tuberosum subsp. andigenum (Juz. & Bukasov) Hawkes], wheat (Triticum aestivum L.), and maize (Zea mays L.) multi environment trials (MET) were used for illustrating the application of the Bayes paradigm. The potato trial included 15 genotypes, but prior information for just three genotypes was used. The wheat trial used prior information on all 10 genotypes included in the trial, whereas for the maize trial, noninformative priors for the nine genotypes was used. Concerning the posterior distribution of the genotypic means, the maize MET with 20 sites gave less disperse posterior distributions of the genotypic means than did the posterior distribution of the genotypic means of the other METs, which included fewer environments. The Bayesian approach allows use of other statistical strategies such as the normal truncated distribution (used in this study). When analyzing grain yield, a lower bound of zero and an upper bound set by the researcher's experience can be used. The Bayesian paradigm offers plant breeders the possibility of computing the probability of a genotype being the best performer. The results of this study show that although some genotypes may have a very low probability of being the best in all sites, they have a relatively good chance of being among the five highest yielding genotypes.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Purpose: To evaluate the influence of heat treatment (HT) procedures of a pre-hydrolyzed silane on bond strength of resin cement to a feldspathic ceramic.Materials and Methods: Ceramic and composite blocks (N = 30) were divided into six groups (n = 5) and subjected to the following conditioning procedures: G1: 9.6% hydrofluoric acid (HF) for 20 s + silane (RelyX Ceramic Primer, 3M ESPE) + resin cement (Panavia F2.0, Kuraray) (control); G2: HF (20 s) + silane + heat treatment in furnace (HTF) (100 degrees C, 2 min) + resin cement; G3: silane + HTF + resin cement; G4-HF (20 s) + silane + heat treatment with hot air (HTA) (50 +/- 5 degrees C for 1 min) + resin cement; G5: silane + HTA + resin cement; G6: silane + resin cement. The microtensile bond strength (MTBS) test was performed using a universal testing machine (1 mm/min). After debonding, the substrate and adherent surfaces were analyzed using a stereomicroscope and SEM to categorize the failure types. The data were statistically evaluated using one-way ANOVA and Tukey's test (5%).Results: The control group (G1) showed no pre-test failures and presented significantly higher mean MTBS (16.01 +/- 1.12 MPa) than did other groups (2.63 +/- 1.05 to 12.55 +/- 1.52 MPa) (p = 0.0001). In the groups where HF was not used, HTF (G3: 12.55 +/- 1.52 MPa) showed significantly higher MTBS than did HTA (G5: 2.63 +/- 1.05 MPa) (p < 0.05). All failure types were mixed, ie, adhesive between the resin cement and ceramic accompanied by cohesive failure in the cement.Conclusion: Heat treatment procedures for the pre-hydrolyzed silane either in a furnace or with the application of hot air cannot replace the use of HF gel for the adhesion of resin cement to feldspathic ceramic. Yet when mean bond strengths and incidence of pre-test failures are considered, furnace heat treatment delivered the second best results after the control group, being considerably better than hot air application.
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Objective. To determine the effects of different aging methods on the degradation and flexural strength of yttria-stabilized tetragonal zirconia (Y-TZP)Methods. Sixty disc-shaped specimens (0, 12 mm; thickness, 1.6 mm) of zirconia (Vita InCeram 2000 YZ Cubes, VITA Zahnfabrik) were prepared (ISO 6872) and randomly divided into five groups, according to the aging procedures (n=10): (C) control; (M) mechanical cycling (15,000,000 cycles/3.8 Hz/200N); (T) thermal cycling (6,000 cycles/5-55 degrees C/30 s); (TM) thermomechanical cycling (1,200,000 cycles/3.8 Hz/200N with temperature range from 5 C to 55 C for 60s each); (AUT) 12h in autoclave at 134 degrees C/2 bars; and (STO) storage in distilled water (37 degrees C/400 days). After the aging procedures, the monoclinic phase percentages were evaluated by X-ray diffraction (XRD), and topographic surface analysis was performed by 3D profilometry. The specimens were then subjected to biaxial flexure testing (1 mm/min, load 100 kgf, in water). The biaxial flexural strength data (MPa) were analyzed by 1-way ANOVA and Tukey's test (alpha = 0.05). The data for monoclinic phase percentage and profilometry (Ra) were analyzed by Kruskal-Wallis and Dunn's tests.Results. ANOVA revealed that flexural strength was affected by the aging procedures (p = 0.002). The M (781.6 MPa) and TM (771.3 MPa) groups presented lower values of flexural strength than did C (955 MPa), AUT (955.8 MPa), T (960.8 MPa) and STO (910.4 MPa). The monoclinic phase percentage was significantly higher only for STO (12.22%) and AUT (29.97%) when compared with that of the control group (Kruskal-Wallis test, p = 0.004). In addition, the surface roughnesses were similar among the groups (p = 0.165).Signcance. Water storage for 400 days and autoclave aging procedures induced higher phase transformation from tetragonal to monoclinic; however, they did not affect the flexural strength of Y-TZP ceramic, which decreased only after mechanical and thermomechanical cycling. (C) 2014 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.
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Pós-graduação em Odontologia Restauradora - ICT
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Objective: The purpose of this study was to assess the influence of conditioning methods and thermocycling on the bond strength between composite core and resin cement. Material and Methods: Eighty blocks (8x8x4 mm) were prepared with core build-up composite. The cementation surface was roughened with 120-grit carbide paper and the blocks were thermocycled (5,000 cycles, between 5 degrees C and 55 degrees C, with a 30 s dwell time in each bath). A layer of temporary luting agent was applied. After 24 h, the layer was removed, and the blocks were divided into five groups, according to surface treatment: (NT) No treatment (control); (SP) Grinding with 120-grit carbide paper; (AC) Etching with 37% phosphoric acid; (SC) Sandblasting with 30 mm SiO2 particles, silane application; (AO) Sandblasting with 50 mu m Al2O3 particles, silane application. Two composite blocks were cemented to each other (n=8) and sectioned into sticks. Half of the specimens from each block were immediately tested for microtensile bond strength (mu TBS), while the other half was subjected to storage for 6 months, thermocycling (12,000 cycles, between 5 degrees C and 55 degrees C, with a dwell time of 30 s in each bath) and mu TBS test in a mechanical testing machine. Bond strength data were analyzed by repeated measures two-way ANOVA and Tukey test (alpha=0.05). Results: The mu TBS was significantly affected by surface treatment (p=0.007) and thermocycling (p=0.000). Before aging, the SP group presented higher bond strength when compared to NT and AC groups, whereas all the other groups were statistically similar. After aging, all the groups were statistically similar. SP submitted to thermocycling showed lower bond strength than SP without thermocycling. Conclusion: Core composites should be roughened with a diamond bur before the luting process. Thermocycling tends to reduce the bond strength between composite and resin cement.
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This study evaluated the influence of different forms of heat treatment on a pre-hydrolyzed silane to improve the adhesion of phosphate monomer-based (MDP) resin cement to glass ceramic. Resin and feldspathic ceramic blocks (n=48, n=6 for bond test, n=2 for microscopy) were randomly divided into 6 groups and subject to surface treatments: G1: Hydrofluoric acid (HF) 9.6% for 20 s + Silane + MDP resin cement (Panavia F); G2: HF 9.6% for 20 s + Silane + Heat Treatment (oven) + Panavia F; G3: Silane + Heat Treatment (oven) + Panavia F; G4: HF 9.6% for 20 s + Silane + Heat Treatment (hot air) + Panavia F; G5: Silane + Heat Treatment (hot air) + Panavia F; G6: Silane + Panavia F. Microtensile bond strength (MTBS) test was performed using a universal testing machine (1 mm/min). After debonding, the substrate and adherent surfaces were analyzed using stereomicroscope and scanning electron microscope (SEM) to categorize the failure types. Data were analyzed statistically using two-way test ANOVA and Tukey's test (=0.05). Heat treatment of the silane containing MDP, with prior etching with HF (G2: 13.15 ± 0.89a; G4: 12.58 ± 1.03a) presented significantly higher bond strength values than the control group (G1: 9.16 ± 0.64b). The groups without prior etching (G3: 10.47 ± 0.70b; G5: 9.47 ± 0.32b) showed statistically similar bond strength values between them and the control group (G1). The silane application without prior etching and heat treatment resulted in the lowest mean bond strength (G6: 8.05 ± 0.37c). SEM analysis showed predominantly adhesive failures and EDS analysis showed common elements of spectra (Si, Na, Al, K, O, C) characterizing the microstructure of the glass-ceramic studied. Heat treatment of the pre-hydrolyzed silane containing MDP in an oven at 100 °C for 2 min or with hot air application at 50 ± 5 ºC for 1 min, was effective in increasing the bond strength values between the ceramic and resin cement containing MDP.
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Hay un ejemplar encuadernado con: Noticias que se proponen (XVII/724).
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Sign.: []2, A-T2
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Sign.: A-N2
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Sign.: [ ]2, B-Z2, 2A-2D2
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Sign.: A-F2 (la última h.en blanco)
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Texto fechado en Valencia a 7 de Julio de 1753