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For energy‐efficient and high‐power illumination systems, phosphor materials have attracted huge research attention over the recent decades. Herein, applying the first‐principles method, we investigate and predict the optoelectronic and structural properties of light‐harvesting phosphors Z2SiF6 (Z = K, Li, Na, Rb) as promising candidates for weight‐light‐emitting diodes w‐LEDs. The calculated direct energy band gaps are of order 1.56, 1.461, 1.479, and 1.585 eV for Z2SiF6 (Z = K, Li, Na, Rb), respectively, thus rendering the compound's semiconducting nature suitable for optoelectronic applications. Calculated structural properties show that Rb2SiF6 is the most stable compound among Z2SiF6 (Z = K, Li, Na, Rb). The optical properties in the energy range of 0–14 eV have been investigated using the well‐known (GGA) formulism available in the literature. Studied compounds are active optical materials as the value of their refractive index nω is between 1.0 and 2.0. Based on investigated optical parameters, we can say that Z2SiF6 (Z = K, Li, Na, Rb) are potential candidates for optoelectronic device applications like white LEDs (w‐LEDs). Thermodynamic parameters of Z2SiF6 (Z = K, Li, Na, Rb) are provided to establish the thermodynamic stability of these compounds. [ABSTRACT FROM AUTHOR]

Lanthanum (La) supported on tin oxide-titanium oxide ( SnO2-TiO2 ) nanoparticles were prepared by a sol-gel method followed by a hydrothermal method. Effect of different solvents (ethyl acetate, benzyl alcohol, ethylene glycol) on the particle size and catalytic activity was investigated. The nanomaterial was characterized by transmission electron microscopy, powder X-ray diffraction, scanning electron microscopy, fourier transform infrared spectroscopy, and energy dispersive X-ray. The catalytic and optical properties were studied using solid-phase spectrophotometry and ultraviolet-visible spectroscopy, respectively. Gas chromatography-mass spectrometry ( GC-MS) was used to detect the intermediates during the catalytic degradation of methylene blue. It was observed that with decrease in the dielectric constant ( ε) of the solvent, the bandgap and particle size decrease and catalytic efficiency increases. Hence, the highest catalytic activity was observed with the solvent having the least dielectric constant. [ABSTRACT FROM AUTHOR]

The article highlights a book exhibition and different competitions held at the International School of Choueifat library in Lahore, Pakistan in April 2007. The facility was decorated with bookstalls, posters of subjects, pictures of popular children's stories, maps, charts and other materials. Seating arrangements were also provided for the readers in the library. Competitions for the students grade 2-13 during the book exhibition included mazes, story writing and a library scavenger hunt. At the end of these activities, prizes were distributed to the winners and certificates were given to all the participants.