RESUMO
Low-temperature lead-free silver pastes deserve thorough investigation for sustainable development and application of MgTiO3 ceramics in electronic devices. In this study, a series of Bi2O3-B2O3-ZnO-SiO2-Al2O3-CaO glasses with suitable softening temperatures were prepared via melt quenching using a type of micrometer silver powder formed by silver nanoparticle aggregates. The composite pastes containing silver powder, Bi2O3 glass powder and an organic vehicle were then screen-printed. The effects of glass powder concentration and sintering temperature on the microstructure of the surface interface were also investigated. The results showed that the silver paste for microwave dielectric ceramic filters (MgTiO3) possessed good electrical conductivity (2.28 mΩ/â¡) and high adhesion (43.46 N/mm2) after medium temperature (670 °C) sintering. Thus, this glass powder has great application potential in non-toxic lead-free silver pastes for metallization of MgTiO3 substrates.
RESUMO
OBJECTIVE: To establish a protocol of rapid clonal propagation of Dioscorea zingiberensis using mature leaves as explants. METHOD: Out the optimal hormone combinations for callus induction, adventitious bud initiation, adventitious bud multiplication and rooting were found out by using MS medium with the macroelements at half strength as basal medium and studying the effects of BA, NAA and IBA on the processes. RESULT AND CONCLUSION: More than 80% of leaf explants formed callus when they were cultured on the media containing 1.0 - 5.0 mg x L(-1) BA and 1.0 - 2.0 mg x L(-1) NAA for 60 days; more than 60% of calli initiated adventitious buds within 50 days after they were transferred to the media containing 2.0 - 5.0 mg x L(-1) BA and 0.2 - 0.5 mg L(-1) NAA; all the adventitious buds rooted well after they were planted on the medium with 2.0 mg x L(-1) IBA for 20 days; the regenerated plantlets grew vigorously after they were transplanted and the survival rate was up to 80%.
