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In the present work, a new series of Smx (x = 1, 6 and 12 wt.%) doped SrO:CoO (1:1) nanocrystals (NCs) have been synthesized by microwave-assisted method. The as-synthesized Smx:SrO@CoO NCs were characterized by XRD (X-ray diffraction), UV–visible, SEM (scanning electron microscopy), XPS (X-ray photoelectron spectroscopy), BET (Brunauer–Emmett–Teller) and EDX (energy-dispersive X-ray) spectroscopic investigations. Irregular shaped morphology was revealed from SEM micrographs with average size of the agglomerates ~ 70 nm. XRD patterns confirmed the formation of mixed phase of monoclinic and tetragonal crystal structure. Blueshift in optical absorptivity resulted as Sm concentration increases in NCs and direct optical band gap decreases from 3.12 to 2.21 eV. Photoluminescence (PL) studies showed strong near edge ultraviolet green-yellow emissions for Sm6 wt.% and12 wt.%:SrO@CoO NCs when excited at 220, 250, 280 nm (λexcitation). Sm12 wt.%:SrO@CoO NCs showed visible range weak band emissions due to crystal defect and formation of oxygen vacancies. Raman studies of Smx:SrO@CoO showed longitudinal optical mode which confirmed the formation of oxygen vacancies. Raman spectroscopy also revealed the presence of Sm-O-Sm, Sr-O-Sr and Co-O bonds in the crystal lattice. In addition Sm6 wt.% and12 wt.%:SrO@CoO NCs showed highest sensitivity (0.10, at 94 µ-ohm and 0.082, at 253 µ-ohm), response (88.9 and 82.7), and had extremely low time parameters (response time of 12, 20 s and recovery time of 24, 44 s) towards O-xylene gas when subjected for detection of its sensitivity in presence of other volatile gases. Moreover sensor exhibited excellent repeatability and restoration. The wide band gap Smx:SrO@CoO NCs can find applications in the field of high resistive sensors, display technologies, LEDs, etc. [ABSTRACT FROM AUTHOR]

A bacteriophage, designated UZ1 and showing lytic activity against a clinically important strain (BE1) ofEnterobacter aerogeneswas isolated from hospital sewage. The stability and lytic activity against this strain under simulated gastro-intestinal conditions was evaluated. After addition of bacteriophage UZ1 to a liquid feed at gastric pH 2, the phage was immediately inactivated and could not be recovered. However, by use of an antacid to neutralize stomach acidity, no significant changes in phage titer were observed after 2 h incubation at 37 °C. After supplementing pancreatic juice and further incubation for 4 h, the phage titer remained stable. The persistence of UZ1 in a mixed microbial ecosystem that was representative for the large intestine was monitored using an in vitro simulation of the human intestinal microbial ecosystem. A pulse administration of bacteriophage UZ1 at a concentration of 105 plaque-forming units (PFU)/ml to reactor 3 (which simulates the ascending colon) showed that, in the absence of the host, bacteriophage UZ1 persisted for 13 days in the simulated colon, while the theoretical washout was calculated at 16 days. To assess its lytic activity in an intestinal microbial ecosystem, a green fluorescent protein (gfp)-labeledE. aerogenesBE1 strain was constructed andgfp-specific primers were designed in order to quantify the host strain using real-time PCR. It was observed that bacteriophage UZ1 was able to replicate and showed lytic activity againstE. aerogenesBE1/gfpin an intestinal microbial ecosystem. Indeed, after 17 h a 2 log unit reduction ofE. aerogenesBE1/gfpwas measured as compared with the assay without bacteriophage UZ1, while the phage titer increased by 2 log units at an initial multiplicity of infection of 0.07 PFU/colony-forming unit. This is the first report of an in vitro model to study bacteriophage activity in the complex intestinal microbial community. [ABSTRACT FROM AUTHOR]