RESUMEN
Spherical Zn2 SiO4 : Eu3+ phosphors were prepared by a Pechini sol-gel process. The microstructure and luminescent properties of the obtained Zn2 SiO4 : Eu3+ particles were well characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and photoluminescence (PL) spectra. The results of SEM demonstrated that the Zn2 SiO4 : Eu3+ particles with a diameter about 1 -3microm, which have spherical morphology, emitted an intensive red light emission at 613 nm under excitation at 395 nm. Besides, the effects of the Eu3+ concentration, annealing temperature and charge compensators of Li+ ions on the PL emission intensities were investigated in detail. The investigation showed that the PL intensity increased with the annealing temperature increasing. At the same time, the PL intensity firstly increased and then decreased with the Eu3+ and Li+ concentration increasing.
RESUMEN
Bacillus subtilis spore preparations are promising probiotics and biocontrol agents, which can be used in plants, animals, and humans. The aim of this work was to optimize the nutritional conditions using a statistical approach for the production of B. subtilis (WHK-Z12) spores. Our preliminary experiments show that corn starch, corn flour, and wheat bran were the best carbon sources. Using Plackett-Burman design, corn steep liquor, soybean flour, and yeast extract were found to be the best nitrogen source ingredients for enhancing spore production and were studied for further optimization using central composite design. The key medium components in our optimization medium were 16.18 g/l of corn steep liquor, 17.53 g/l of soybean flour, and 8.14 g/l of yeast extract. The improved medium produced spores as high as 1.52 +/- 0.06 x 10(10) spores/ml under flask cultivation conditions, and 1.56 +/- 0.07 x 10(10) spores/ml could be achieved in a 30-l fermenter after 40 h of cultivation. To the best of our knowledge, these results compared favorably to the documented spore yields produced by B. subtilis strains.
Asunto(s)
Bacillus subtilis/fisiología , Medios de Cultivo/química , Esporas Bacterianas/fisiología , Bacillus subtilis/crecimiento & desarrollo , Técnicas Bacteriológicas , Reactores Biológicos , Biotecnología , Carbono/metabolismo , Fibras de la Dieta , Fermentación , Harina , Microbiología de Alimentos , Modelos Biológicos , Modelos Estadísticos , Nitrógeno/metabolismo , Proyectos de Investigación , Glycine max , Zea maysRESUMEN
We have strategically incorporated three different fluorophores at tren to construct a multi-energy donor/acceptor "smart" probe L. This probe operates by using three-dimensional scales (response time, wavelength and fluorescence intensity) which allows for the selective recognition and discrimination of the Cu2+, Hg2+, Fe3+ and F- ions.