Thallium-doped cesium iodide (CsI(Tl)) screens are widely used in X-ray imaging devices because of the columnar structure of CsI(Tl) layer, but few reports focus on the optical role of the substrate in the screen system. In this paper, four substrates including fused silica (SiO2), silver-film coated SiO2, graphite (C) and fiber optic plate (FOP) are used to fabricate CsI(Tl) screens by thermal evaporation. Their imaging performance is evaluated by relative light output (RLO), modulation transfer function (MTF), normalized noise power spectrum (NNPS) and noise equivalent quanta (NEQ). The results reveal that although CsI(Tl) film on graphite plate yields images with the lowest light output, it presents relatively higher spatial resolution and better signal-to-noise characteristics. However, films on SiO2 plate obtain low MTF but high NNPS curves, whether or not coated with silver film. Furthermore, scintillation screens on FOP have bright images with low NNPS and high NEQ, but have the lowest MTF. By controlling the substrate optical features, CsI(Tl) films can be tailed to suit a given application.
In recent years, there are many reports about the synthesis of 2,3-disubstituted indole by cyclization. Most of these approaches are catalyzed by different transition metals and metal-free catalysis conditions using phenylnydrazines, anilines and nitrobenzenes as main substrates. These methods have been a powerful strategy to obtain 2,3-disubstituted indoles. The recent progress of the synthesis of 2,3-disubstituted indoles by cyclization with the different substrates systems is summarized.
Reduced Schiff base ligand by condensation of phenylalanine analogue containing 2,3-diaminopropionic acid (DAP) with salicylaldehyde and its oxovanadium(IV) complex have been prepared. Chemical and structural properties were fully characterized. Density functional theory was used to pin down the structure combined with IR. The natural bond orbital analysis and energy calculations indicate that tetracoordinated complex of R-type is the most probable structure where vanadium atom is coordinated to 2 £ O phenolate and 2 £ N imine of the ligand. By biological evaluation, the metal complex exhibits antibacterial activity against four bacterial strains and antitumor activity against two tumor cell lines.
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