Objetivo: testar a hipótese nula de que o processo de envelhecimento em braquetes autoligáveis não é superior ao de braquetes convencionais. Métodos: Vinte e cinco braquetes metálicos convencionais (GN, 3M/Unitek; GE, GAC; VE, Aditek) e 25 autoligáveis (SCs, 3M/Unitek; INs, GAC; ECs, Aditek) de três fabricantes (n = 150) foram submetidos ao envelhecimento em solução de NaCl à temperatura constante de 37 ± 1ºC, durante 21 dias. O conteúdo de íons níquel, cromo e ferro na solução coletada com 7, 14 e 21 dias foi quantificado por meio de espectrofotometria de absorção atômica. Depois de completado o processo de envelhecimento, os braquetes foram analisados com microscópio eletrônico de varredura (MEV), em magnificações de 22x e de 1.000x. Resultados: comparando-se a liberação de metais por braquetes autoligáveis e convencionais do mesmo fabricante, observou-se que o grupo SCs liberou mais níquel (p < 0,05) que o grupo GN após 7 e 14 dias, mas menos cromo (p < 0,05) após 14 dias e menos ferro (p < 0,05) nos três períodos experimentais. O grupo INs liberou menos ferro (p < 0,05) que o grupo GE após 7 dias, e menos níquel, cromo e ferro (p < 0,05) após 14 e 21 dias. O grupo ECs liberou mais níquel, cromo e ferro (p < 0,05) que o grupo VE após 14 dias; entretanto, liberou menos níquel e cromo (p < 0,05) após 7 dias e menos cromo e ferro (p < 0,05) após 21 dias. A análise no MEV demonstrou alterações na topografia da superfície de braquetes convencionais e autoligáveis. Conclusões: o processo de envelhecimento em braquetes autoligáveis não foi superior ao de braquetes convencionais do mesmo fabricante. A hipótese nula está aceita.

Objective: To test the null hypothesis that the aging process in self-ligating brackets is not higher than in conventional brackets. Methods: Twenty-five conventional (GN-3M/Unitek; GE-GAC; VE-Aditek) and 25 self-ligating (SCs-3M/Unitek; INs-GAC; ECs-Aditek) metal brackets from three manufacturers (n = 150) were submitted to aging process in 0.9% NaCl solution at a constant temperature of 37 ± 1ºC for 21 days. The content of nickel, chromium and iron ions in the solution collected at intervals of 7, 14 and 21 days was quantified by atomic absorption spectrophotometry. After the aging process, the brackets were analyzed by scanning electron microscopy (SEM) under 22X and 1,000X magnifications. Results: Comparison of metal release in self-ligating and conventional brackets from the same manufacturer proved that the SCs group released more nickel (p < 0.05) than the GN group after 7 and 14 days, but less chromium (p < 0.05) after 14 days and less iron (p < 0.05) at the three experimental time intervals. The INs group released less iron (p < 0.05) than the GE group after 7 days and less nickel, chromium and iron (p < 0.05) after 14 and 21 days. The ECs group released more nickel, chromium and iron (p < 0.05) than the VE group after 14 days, but released less nickel and chromium (p < 0.05) after 7 days and less chromium and iron (p < 0.05) after 21 days. The SEM analysis revealed alterations on surface topography of conventional and self-ligating brackets. Conclusions: The aging process in self-ligating brackets was not greater than in conventional brackets from the same manufacturer. The null hypothesis was accepted.

O objetivo deste estudo foi testar a hipótese nula de que não há nenhuma diferença de liberação de flúor entre cimentos de ionômero de vidro reforçados com resina (CIVRRs) e entre compósitos em longo prazo. Os materiais foram divididos em 5 grupos: um compósito não liberador de flúor - Grupo TXT (Transbond XT), um compósito liberador de flúor - Grupo QC (Quick-Cure), e três CIVRRs - Grupos FOLC, FOB e MC (Fuji Ortho LC, Fuji Ortho Band e Multi-Cure). A liberação de flúor foi medida em intervalos de tempo de 1 h, 1, 7, 14, 21 e 29 dias, seguido por outras avaliações realizadas aos 6, 12, 18, 24 e 30 meses, utilizando um eletrodo íon seletivo conectado a um analisador de íons. Liberação de flúor e experimentos de re-liberação foram avaliados usando o teste de Kruskal-Wallis e teste Mann-Whitney com correção de Bonferroni. A quantidade de flúor liberado pelo FOB foi maior em comparação com os outros adesivos (p=0,001). Em longo prazo, FOLC e MC demonstraram um desempenho semelhante (p>0,05). Os compósitos liberaram uma baixa quantidade de fluoreto, no entanto, a capacidade de captação do íon fluoreto e re-liberação do QC foi estatisticamente significante (p<0,05) durante o experimento. Em conclusão, a hipótese nula foi rejeitada, o CIVRR Fuji Ortho Band e o compósito Quick-Cure apresentaram maior liberação e capacidade de re-liberação de flúor quando recarregados.

The aim of this study was to test the null hypothesis that there is no difference in fluoride release between resin-modified glass ionomer cements (RMGICs) and composites in the long term. The materials were divided into 5 groups: a nonfluoride-releasing composite - Group TXT (Transbond XT), a fluoride-releasing composite - Group QC (Quick-Cure), and three RMGICs - Groups FOLC, FOB and MC (Fuji Ortho LC, Fuji Ortho Band, and Multi-Cure). Fluoride release was measured at time intervals of 1 h, 1, 7, 14, 21 and 29 days, followed by further evaluations performed at 6, 12, 18, 24 and 30 months using selective ion electrodes connected to an ionic analyzer. Fluoride releasing and re-releasing experiments were analyzed using the Kruskal-Wallis test and Mann-Whitney test with the Bonferroni correction. The amount of fluoride released by FOB was larger in comparison with the other adhesives (p=0.01). In the long-term, FOLC and MC had a similar performance (p>0.05). The composites presented a low fluoride release, but fluoride ion uptake and re-release capacity of QC was statistically significant (p<0.05) during the experiment. In conclusion, the null hypothesis was rejected, the RMGIC Fuji Ortho Band and the composite Quick-Cure presented greater fluoride release and re-release capacity when recharged.

OBJECTIVE: The aim of this study was to evaluate the antimicrobial and fluoride releasing capacity of 3 bonding materials. MATERIAL AND METHODS: Thirty nine specimens with standardized surface smoothness and dimensions were prepared. The antimicrobial capacity of the materials against S. mutans, L. casei and C. albicans was evaluated by determining the percentage of growth inhibition of these microorganisms in an inoculated medium, obtained by optical density readouts on a spectrophotometer. The potential to interfere in microbial growth on the surface of the studied materials was observed by means of scanning electron microscopy (SEM). The fluoride release capacity in ultrapure water for 14 days was analyzed by means of ion chromatography. RESULTS: The PLUS group presented the highest percentage of microbial inhibition and the most contamination-free surface. The FUJI group presented the best fluoride release capacity. CONCLUSIONS: The TransbondTM Plus Color Change was the one that presented the best general behavior considering the evaluated aspects.

OBJETIVO: o objetivo desse estudo foi avaliar a liberação de flúor dos seguintes três cimentos de ionômero de vidro, com proteção imediata de verniz fluoretado (Cavitine, S. S. White): Meron / VOCO (Grupo M); Vidrion C / S. S. White (Grupo V); e Ketac Cem / 3M ESPE (Grupo KC). MÉTODOS: a liberação de flúor foi medida durante 60 dias, através de eletrodo íon seletivo conectado a um analisador de íons. Após quatro semanas, os corpos de prova foram expostos a uma solução de fluoreto de sódio a 0,221% (1.000ppm de flúor). RESULTADOS: os resultados evidenciaram que os cimentos atingiram o pico máximo de liberação de flúor com 24h após a presa inicial. Houve diferença estatisticamente significativa entre os grupos, quanto à quantidade de flúor liberado após as aplicações de flúor, do 31º ao 60° dia (p > 0,05). CONCLUSÃO: os cimentos Meron e Vidrion apresentaram maior capacidade de captação e liberação de flúor, em comparação ao cimento Ketac Cem.

OBJECTIVES: The objective of the authors was to evaluate fluoride release of 3 glass ionomer cements with immediate protection of fluoride varnish (Cavitine, SS White), divided into 3 groups: Group M (Meron, VOCO), Group V (Vidrion C, SS White) and Group KC (Ketac-Cem, 3M ESPE). METHODS: Fluoride release was measured during 60 days by means of an ion-selective electrode connected to an ion analyzer. After 4 weeks, the test specimens were exposed to a solution of 0.221% sodium fluoride (1000 ppm of fluoride). RESULTS: Results showed that the cements reached a maximum peak of fluoride release in a period of 24 h. There was a statistically significant difference between the amount of fluoride released after the applications of fluoride among the groups from the 31st to 60th day (p> 0.05). CONCLUSION: The Vidrion C and Meron cements showed better performance to uptake and release fluoride when compared with Ketac-Cem cement.

O objetivo deste estudo foi testar a hipótese que não há diferença no desempenho dos cimentos de ionômero de vidro reforçados com resina entre si quanto à liberação de flúor antes e após recarga com flúor. Os materiais foram divididos em 5 grupos: 2 cimentos de ionômero de vidro reforçados com resina utilizados para cimentação de bandas ortodônticas: Grupo FOB (Fuji Ortho Band) e Grupo MCB (Multi-Cure Glass Ionomer Orthodontic Band Cement); 2 cimentos de ionômero de vidro reforçados com resina e 1 compósito utilizados para colagem de bráquetes ortodônticos: Grupo OGLC (Ortho Glass LC), Grupo FOLC (Fuji Ortho LC); e Grupo TXT (Transbond XT), respectivamente. A liberação de flúor foi medida durante 60 dias, através de eletrodo íon seletivo conectado a um analisador de íons. Após 4 semanas, os corpos de prova foram expostos a solução de fluoreto de sódio à 0,221%. Os resultados evidenciaram que os cimentos atingiram o pico máximo de liberação de flúor com 24 h após presa inicial. Não houve diferença estatisticamente significante entre a quantidade de flúor liberado após as recargas de fluoreto de sódio entre os grupos FOB e OGLC do 31° ao 36° dia (p>0.05). Concluindo os cimentos FOB e OGLC apresentaram maior capacidade de captação e liberação de flúor comparada aos outros CIVRRs.

The aim of this study was to test the hypothesis that there is no difference in the fluoride release behavior of resin-reinforced glass ionomer cements before or after fluoride recharge. The materials were divided into 5 groups: 2 resin-reinforced glass ionomer cements used for attaching orthodontic bands, that is, group FOB (Fuji Ortho Band) and group MCB (Multi-Cure Glass Ionomer Orthodontic Band Cement); 2 resin-reinforced glass ionomer cements and a composite used for bonding orthodontic brackets, that is, group OGLC (Ortho Glass LC), group FOLC (Fuji Ortho LC), and group TXT (Transbond XT), respectively. Fluoride release was measured during a 60-day period by using selective ion electrodes connected to an ionic analyser. After 4 weeks, the samples were exposed to 0.221% sodium fluoride solution. The results showed that cements achieved a maximum fluoride release 24 h after initial setting. No statistically significant differences were observed between groups FOB and OGLC regarding the amount of released fluoride following fluoride recharge from day 31 to day 36 (p>0.05). In conclusion, FOB and OGLC cements showed a higher capacity of capturing and releasing fluoride compared to the other cements studied.

Lettuce is worldwide known as the most important vegetable. In this context, most farmers are searching new techniques for best quality products including hydropony. However, nitrate is of great concern, since it has a negative impact on human metabolism. The main objective of the present work was to evaluate the nitrate content of lettuce produced by conventional and hydroponic systems. The determination was conducted by ion chromatography and a new method of extraction was tested using microwave oven digestion. The results indicated that nitrate level produced in the conventional system was lower than in the hydroponic system.

This work presents a little of the history which marked the development of the dairy industry in Brazil and in the world. It shows problems and solutions related to the preservation of milk. In general, it also describes the traditional manufacture of cheese and applications of membrane technology as an auxiliary tool in the processing of some types of cheese.

Neste trabalho, determinou-se o nível de chumbo (Pb) presente no ar em ambientes externos e na poeira doméstica de residências localizadas próximo a uma reformadora de baterias (RB). Uma das principais fontes de exposição ao Pb são empresas do setor de RB, que ainda utilizam processos e tecnologia obsoletos em instalações precárias. Na área externa à RB foram realizadas coletas em seis pontos localizados a aproximadamente 25m e a 500m da RB. Os resultados obtidos mostram que o limite para Pb no ar atmosférico (Pb-Ar) de 1,5µg Pb.m-3 foi excedido em 50% das amostras coletadas, variando de 0,03 a 183,3µg Pb.m-3. As coletas nas dependências internas e externas das residências foram realizadas em seis pontos de quatorze residências localizadas a aproximadamente 25m, 50m e a 500m da RB. O limite de Pb na poeira doméstica (Pb-Pd) de 1.500µg Pb.m-2 foi excedido em 44% das amostras coletadas, apresentando valores variáveis de 2,2 a 54.338,9µg Pb.m-2.

This study measured lead concentrations in both the outdoor air and household dust from houses located around a lead-acid battery repair shop. Such installations are one of the largest sources of lead exposure, since outdated technology is still used, coupled with the lack of strict air-quality control programs. Measurements of the air lead concentration around the repair shop were carried out at 6 points, approximately 25 and 500m from the shop. Over 50% of the air samples exceeded the limit of 1.5µg Pb.m-3 (range 0.03 - 183.3µg Pb.m-3). House dust samples were collected from 6 places in houses located at approximately 25, 50, and 500m from the repair shop, and the concentration of 1,500µg Pb.m-2 for lead in house dust was exceeded in 44% of the samples, with results varying from 2.2 to 54,338.9µg Pb.m-2.

Neste trabalho, determinou-se o nível de chumbo (Pb) presente no ar em ambientes externos e na poeira doméstica de residências localizadas próximo a uma reformadora de baterias (RB). Uma das principais fontes de exposição ao Pb são empresas do setor de RB, que ainda utilizam processos e tecnologia obsoletos em instalações precárias. Na área externa à RB foram realizadas coletas em seis pontos localizados a aproximadamente 25m e a 500m da RB. Os resultados obtidos mostram que o limite para Pb no ar atmosférico (Pb-Ar) de 1,5µg Pb.m-3 foi excedido em 50% das amostras coletadas, variando de 0,03 a 183,3µg Pb.m-3. As coletas nas dependências internas e externas das residências foram realizadas em seis pontos de quatorze residências localizadas a aproximadamente 25m, 50m e a 500m da RB. O limite de Pb na poeira doméstica (Pb-Pd) de 1.500µg Pb.m-2 foi excedido em 44% das amostras coletadas, apresentando valores variáveis de 2,2 a 54.338,9µg Pb.m-2.

This study measured lead concentrations in both the outdoor air and household dust from houses located around a lead-acid battery repair shop. Such installations are one of the largest sources of lead exposure, since outdated technology is still used, coupled with the lack of strict air-quality control programs. Measurements of the air lead concentration around the repair shop were carried out at 6 points, approximately 25 and 500m from the shop. Over 50% of the air samples exceeded the limit of 1.5µg Pb.m-3 (range 0.03 - 183.3µg Pb.m-3). House dust samples were collected from 6 places in houses located at approximately 25, 50, and 500m from the repair shop, and the concentration of 1,500µg Pb.m-2 for lead in house dust was exceeded in 44% of the samples, with results varying from 2.2 to 54,338.9µg Pb.m-2.

In the oil industry, the paraffination phenomenon is a major problem during oil production, displacement and treatment. Paraffin deposition in subsea flowlines, surface equipment, production string or even in the reservoir, can cause significant and increasing oil losses. To minimize paraffin precipitation, the application of magnetic field in the petroleum path has been suggested based on empiric studies. In this study, we assembled a labscale magnetic conditioner to determine the influence of magnetic field on the physical-chemical properties of two fluids : oil and a paraffin mixture. We observed that magnetic field reduce sample aparent viscosity due to crystal morphology alteration.