RESUMO
Nd3+-Doped yttrium aluminium garnet and Eu3+-Nd3+-co-doped yttrium aluminium garnet were synthesized using an environmentally friendly sol-gel method at low temperatures. The results of X-ray diffraction (XRD) analysis of the powders sintered at 1000 °C showed the purity and formation of monophasic compounds. The phase composition and purity confirmation of the samples were also characterized via FTIR spectroscopy. Desirable microstructural features and particle size of phosphorous materials of the polycrystalline samples were studied via scanning electron microscopy (SEM). The local environments of Eu3+ and Nd3+ activator ions of the garnets structure compounds were investigated using nuclear magnetic resonance (NMR) spectroscopy. The local environments of the small number of substituted phosphorous ions (Eu3+ and Nd3+) in YAG were shown to critically influence optical properties. Structural features of garnets were found to correlate with their luminescence properties. The luminescence properties were characterized using the results from a photoluminescence (PL) study. Effective concentration of luminescent ion - Nd in YAG was, observed and the optimum ratio between two phosphorous (Eu3+ and Nd3+) was analysed. The transition among europium and neodymium phosphorus was determined.
RESUMO
Styrian oil pumpkin seedlings (Cucurbita pepo L. subsp. pepo var. styriaca GREB: .) were treated for 48 h with 1 mM OTC (L-2-oxothiazolidine-4-carboxylic acid) in order to artificially increase cellular glutathione content. They were inoculated with zucchini yellow mosaic virus (ZYMV) 10 days later. The effects of OTC treatment and ZYMV infection on glutathione levels were examined at the subcellular level by immunogold labeling of glutathione using a transmission electron microscope (TEM). These effects were further tested at the whole-tissue level by high performance liquid chromatography (HPLC). Such tests were carried out a) on roots, cotyledons and the first true leaves immediately after OTC treatment in order to analyze to which extent OTC increases glutathione levels in different cell compartments as well as in the whole organ; and b) in older and younger leaves and in roots three weeks after ZYMV inoculation in order to study how possible effects of OTC on symptom development would correlate with glutathione levels at the subcellular level and in the whole organ. Immunocytological and biochemical investigations revealed that, 48 h after OTC treatment, glutathione content had increased in all investigated organs, up to 144% in peroxisomes of cotyledons. Three weeks after ZYMV inoculation, glutathione labeling density had significantly increased within intact cells of infected leaves, up to 124% in the cytosol of younger leaves. Roots showed decreased amounts of glutathione in the TEM. Biochemical studies revealed that OTC treatment resulted in 41 and 51% higher glutathione content in older and younger ZYMV-infected leaves, respectively, in comparison to untreated and ZYMV-infected plants. Evaluation of symptom development at this point revealed that all untreated ZYMV-infected plants had symptoms, whereas only 42% of OTC-treated ZYMV-infected plants showed signs of symptoms. Quantification of ZYMV particles revealed that all organs of OTC-treated and ZYMV-infected plants contained significantly decreased amounts of ZYMV particles over a period of five weeks when compared to the same organs of untreated ZYMV-infected plants. We can conclude that OTC treatment and subsequently elevated glutathione contents within Styrian oil pumpkin plants led to a strong decrease in virus content, which was accompanied by a suppression of ZYMV-induced symptoms as well as reduced and delayed symptom development within plants exhibiting symptoms.