Control of spectroscopic fluorescence parameters of Nd3+ ions as a function of concentration in a SiO2–Na2O–Al2O3–B2O3 glass system

AbstractExperimental evidence of spectroscopic parameter control was observed in Nd3+ ions embedded in a SiO2–Na2O–Al2O3–B2O3 glass system. The parameters Ω2,4,6 and others were determined by the Judd–Ofelt theory. It was found that these parameters were strongly dependent on Nd3+ concentration, indicating a ligand field change. This Letter will present and discuss possible mechanisms responsible for changes in the Judd–Ofelt parameters. Furthermore, non-radiative energy transfer mechanisms such as energy migration, cross relaxation and losses from networked phonons and OH− radicals, will be proposed to explain the observed decrease in 4F3/2→4I11/2 transition lifetime of Nd3+

Optically stimulated luminescence of borate glasses containing magnesia, quicklime, lithium and potassium carbonates

The OSL characteristics of three different borate glass matrices containing magnesia (LMB), quicklime (LCB) or potassium carbonate (LKB) were examined. Five different formulations for each composition were produced using a melt-quenching method and analyzed in terms of both dose-response curves and OSL shape decay. The samples were irradiated using a 90Sr/90Y beta source with doses up to 30 Gy. Dose-response curves were plotted using the initial OSL intensity as the chosen parameter. The OSL analysis showed that LKB glasses are the most sensitive to beta irradiation. For the most sensitive LKB composition, the irradiation process was also done using a 60Co gamma source in a dose range from 200 to 800 Gy. In all cases, no saturation was observed. A fitting process using a three-term exponential function was performed for the most sensitive formulations of each composition, which suggested a similar behavior in the OSL decay for the compositions L30MB and L30CB, as well as the most rapid decay regarding the composition L15KB

Embryo rescue from interspecific crosses in apple rootstocks Resgate de embriões a partir de cruzamentos interespecíficos em porta-enxerto de macieira

The objetive of this work was to rescue immature embryos of apple rootstocks Malus prunifolia (Marubakaido) and Malus pumila (M9) after 40-60 days of pollination and to put them into MS culture media supplemented with agar (6 g L-1) and casein hydrolysate (500 mg L-1). Embryos originated from interspecific crosses and open pollination showed differences in the in vitro responses, depending on the female parent, the developmental stage of the embryo, and the culture medium composition. Embryos of the M. pumila rootstock, rescued within 40 days after pollination and put in culture medium supplemented with indolacetic acid (IAA), gibberellic acid (GA3), kinetin and maltose, resulted in a normal development of plantlets. However, embryos originating from hand-pollination, cultivated in medium supplemented with 14 µM IAA, 5 µM kinetin and 1.5 µM Ga3 (MS1), mainly those of M. prunifolia x M. pumila, showed a high percentage of rusted embryos (96.2%). Embryos from open pollination of M. prunifolia and M. pumila formed calluses. It was possible to identify the influence of the female parent by the enhanced development of M. pumila shoots derived from open or hand-pollination. The crossing of responsive species and the use of the technique of embryo culture provided a rapid and uniform germination and, consequently, the development of fully normal seedlings.<br>O objetivo deste trabalho foi resgatar embriões imaturos de porta-enxertos de macieira Malus prunifolia (Marubakaido) e Malus pumila (M9) depois de 40 e 60 dias de polinização e colocá-los em meio de cultura MS suplementado com ágar (6 g L-1) e hidrolisado de caseína (500 mg L-1). Embriões originados do cruzamento interespecífico dirigido e de polinização aberta mostraram diferenças significativas in vitro, tendo sido observadas diferenças quanto ao progenitor feminino, quanto à fase de desenvolvimento do embrião e à composição do meio de cultura. Embriões do porta-enxerto M. pumila, resgatados aos 40 dias depois da polinização e colocados em meio de cultura suplementado com ácido indolacético (AIA), ácido giberélico (GA3), cinetina e maltose, resultaram em desenvolvimento normal das plantas. Porém, foi observada alta porcentagem de embriões oxidados (96,2%), originados de polinização dirigida, cultivados em meio com 14 µM de AIA, 5 µM de cinetina e 1,5 µM de GA3 (MS1), principalmente para o cruzamento M. prunifolia e M. pumila. Embriões de polinização aberta de M. prunifolia x M. pumila formaram calos. Foi possível identificar a influência do progenitor feminino, pelo incremento de brotações de M. pumila derivada de polinização aberta e dirigida. O cruzamento de espécies responsivas e o uso da técnica de cultura de embrião promoveram germinação rápida e uniforme e, por conseguinte, o desenvolvimento de mudas normais