25 resultados para Beckman pH meter


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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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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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O tratamento de esgotos sanitários e o seu posterior reúso, tornou-se uma alternativa viável para a irrigação, atividade que utiliza em torno de 70 % de toda a água consumida no planeta. Nesse sentido, o objetivo deste estudo foi monitorar durante todo o ciclo do trigo, os teores de Ferro e Manganês, bem como valores de pH e condutividade elétrica da água residuária utilizada para irrigação da cultura por gotejamento. A água residuária utilizada no estudo foi proveniente da Estação de Tratamento de Esgotos (ETE) da cidade de Botucatu-SP. No período de maio a outubro de 2011 a amostragem da água residuária foi realizada semanalmente, na saída da ETE. Foram determinados os seguintes parâmetros: Boro (B), Cobre (Cu), Ferro (Fe), Manganês (Mn) e Zinco (Zn), segundo metodologia adaptada de Malavolta et al. (1997). O pH e a condutividade elétrica (CE) foram determinados com auxilio de um pHmetro e condutivímetro, respectivamente. Não foi observado teores de Fe e Mn e valores de pH que comprometessem o sistema de irrigação, ou seja, que apresentasse alto potencial de risco de obstrução de tubulações e emissores (gotejamento). Os valores de CE indicam que a água residuária pode ser usada no solo, sempre que houver grau elevado de lixiviação, sem maior comprometimento das culturas.

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Objective: The purpose of this study was to evaluate the influence of the addition of 2% chlorhexidine digluconate (CHX) associated with 5% calcium chloride (CaCl2 ) on antimicrobial activity, setting time, pH and calcium release of gray mineral trioxide aggregate (GMTA). Materials and Methods: GMTA powder was mixed with water, 2% CHX alone or 2% CHX combined with 5% CaCl2 . Antimicrobial activity was determined against Enterococcus faecalis (ATCC 29212) strains by agar diffusion test. Data obtained were submitted to kruskal wallis tests. Analysis of the setting time was evaluated by American society for testing and materials C266-03 requirements. The pH and calcium release analysis were evaluated, in 24 h, 7, 14 and 28 days using pH meter equipment and atomic absorption spectrophotometer, respectively. Data obtained were analyzed by ANOVA, in 5% significance level. Results: Significant differences were seen (P < 0.01) among the zones of bacterial growth inhibition produced by 5% CaCl2 + 2% CHX combination against E. faecalis when compared with water (P < 0.05). Regarding the setting time, that combination had the shortest setting time (P < 0.05). All associations were alkaline and released calcium. No statistical difference was observed between the experimental groups at the different periods of analysis (P > 0.05). Conclusion: Combination of 5% CaCl2 + 2% CHX reduced the setting time and enhanced the antimicrobial activity of GMTA without changing the pH and calcium release.

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The purpose of this study was to characterize and to evaluate the bioactivity potential of experimental root canal sealers (ES) based on Portland cement, epoxy resin with nano- and micro-particles of niobium or zirconium oxide used as radiopacifiers in comparison to AH Plus and MTA Fillapex. Methods Specimens of the sealers (10 mm in diameter × 1 mm thick) were prepared and the radiopacity was evaluated according to ISO 6876 (2012) specifications. Characterization of the sealers was performed under the scanning electron microscope (SEM) immediately after setting and after immersion for 28 days in Hank's balanced salt solution (HBSS). In addition X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and Fourier transform infrared (FT-IR) spectroscopy were also performed. The pH and calcium ion release were measured after 1, 7, 14, 21 and 28 days after completion of seating using a digital pH meter and an atomic absorption spectrophotometer, respectively. Results The experimental sealers exhibited an average radiopacity of 2.5 mm thickness of aluminum, which was similar to MTA Fillapex (P > 0.05) and inferior to AH Plus (P < 0.05). AH Plus did not show bioactivity. Although the experimental sealers did not exhibit the formation of hydration product, they encouraged the deposition of crystalline spherical structures of calcium deficient phosphate. The highest pH and calcium release values were observed with the experimental sealers (P < 0.01). ES-Nb-micro was the only sealer to present hexagonal shaped crystal deposition. Significance Novel root canal sealers based on a mixture of Portland cement, epoxy resin and radiopacifier exhibited a degree of bioactivity although no evidence of cement hydration was demonstrated on material characterization. The radiopacifier particle size had limited effect on the sealer microstructure and chemical properties.

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

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)