Exploration of Photoluminescence, Colorimetric, and Decay Performance of Sm-activated CaWO4 Ceramic.

This paper represents structure, photoluminescence, and colorimetric investigations of Sm-activated CaWO4 ceramic made with the help of a solid-state reaction process. Structures of the ceramics are examined through X-ray diffraction spectroscopy. It indicates that these materials have a tetragonal structure and I41/a space group without having any other secondary phase. Energy band gaps are increased with the higher concentrations of Sm dopants. Photoluminescence analyses show that concentration quenching is found at x = 0.02 Sm incorporated CaWO4. The critical distance of energy transfer is obtained as about 20 Å. Q-value is observed approximately equal to 6 which denotes that dipole-dipole interactions occur in the materials that create the critical energy transfer distance in them. Chromaticity values are described in that the ceramics emit orange-red color as well as excellent colorimetric parameters. Quantum efficiency of x = 0.02 Sm composition in CaWO4 is measured under 405 nm EX wavelength. Photoluminescence decay behaviors are observed and average lifetime values are evaluated.

In vitro studies of Bacopa monnieri--an important medicinal plant with reference to its biochemical variations.

Micropropagation of Bacopa monnieri was achieved on MS and B5 medium supplemented with BAP and NAA using leaf explants and nodal segments. Best results were found on MS medium in both the explants with BAP (2.0 mg/l) showing higher percentage of regeneration. Besides that the biochemical parameters, like chlorophyll, carbohydrate, protein, of leaves both in vivo and in vitro have also been carried out in order to establish the sustainability of plants.

Reduced uptake as a mechanism of zinc tolerance in Oscillatoria anguistissima.

Oscillatoria anguistissima could tolerate 50 ppm ZnSO4 x 7H2O, and a zinc-tolerant strain with maximum tolerance concentration (MTC) of 100 ppm ZnSO4 x 7H2O was obtained by stepwise transfer to higher concentrations. The adaptation was irreversible even after three generations in metal-free medium. In the presence of metal, the tolerant strain grew with a shorter lag period of 4 days as against 6 days in the case of the wild strain. The tolerant strain had higher MTC than that of the wild strain for other metals also, viz., Ni2+, Co2+, Cu2+ and Cd2+. The zinc resistance in the tolerant strain was a result of reduced uptake, since around 42% of the total metal was present on the surface as against only 30% in the wild strain. The calcium-stimulated uptake, as observed in the wild strain, was absent in the tolerant strain. Ultrastructural comparisons revealed no structural change in the tolerant strain on exposure to zinc, whereas in the wild strain a thick extracellular matrix was observed.