Assuntos
Implante de Prótese de Valva Cardíaca , Próteses Valvulares Cardíacas , Insuficiência da Valva Mitral , Humanos , Valva Mitral/diagnóstico por imagem , Valva Mitral/cirurgia , Cateterismo Cardíaco , Resultado do Tratamento , Insuficiência da Valva Mitral/diagnóstico por imagem , Insuficiência da Valva Mitral/cirurgiaRESUMO
Six crystal glass compositions containing no added lead were studied with respect to the potential exposure of workers during the cold-end working of crystal type glasses. During cutting and grinding of crystal glass, fine dusts are produced. These may be inhaled by the workers with subsequent partial dissolution of the dusts in the lung fluid. In order to provide a measure of the degree of dissolution in the case of the six crystal glass compositions produced in this work, the release of antimony, barium, silicon, and bismuth was investigated by passing simulated lung fluid over powdered samples of the crystal having a maximum distribution at a diameter of ca. 0.5 microm for a period of 21 days. The results show that it is possible to produce durable glass containing no added lead. While the leaching and weathering of the glass compositions studied here could be correlated with the mole ratio of alkali/silica and the degree of depolymerisation of the silica network, the dissolution of silica in simulated lung fluid seems to be independent of this property.
Assuntos
Líquidos Corporais/metabolismo , Vidro/química , Exposição por Inalação/análise , Chumbo/análise , Pulmão/metabolismo , Simulação por Computador , Poeira/análise , Humanos , Metais Pesados , Microscopia Eletrônica de Varredura , Modelos Biológicos , Exposição Ocupacional , Tamanho da Partícula , Dióxido de SilícioRESUMO
Six crystal glass compositions without added lead were used to prepare standard beakers having a volume of ca. 240 ml. The experimentally determined concentrations of the elements in the glass beakers were in satisfactory agreement with the theoretically predicted values. The degree of leaching of selected elements from these beakers was determined using 4% acetic acid as described in the ISO 7086-1:2000 standard test. In addition, to the degree of leaching by 4% acetic acid, migration into cola, red wine, 40% ethanol and 0.3% citric acid was also determined. Elements tested included antimony, barium, bismuth and zinc as these were considered to be of most interest. The results show that it is possible to produce durable glass containing no added lead. The overall quality of the glasses was good and the concentrations of the various elements migrating (leaching) into the various test solutions used was very small and it is clear that they would not present a hazard to consumers in the event that they were to use glasses of any of these compositions for consumption of either alcoholic or non-alcoholic beverages. The original ISO7086-1:2000 test using a 4% acetic acid leaching solution was developed to test for lead migration from crystal containing added lead and ceramic ware containing lead glazes or colouring. This work also shows that it is an excellent leaching agent for assessing the safety of crystal containing no added lead as it gave the highest degree of migration for all the glass compositions and all the elements tested. In the case of glasses containing ZnO, it was shown that the degree of zinc migration was linearly related to the mole-% of ZnO in the glass. With respect to the durability of glasses, it was shown that the degree of attack increases when the degree of silica depolymerisation increases.
