Physical and optical properties of nanocrystalline calcium ferrite synthesized by the polymerized complex method

Nanocrystalline CaFe2O4 oxide semiconductor with spinel structure was synthesized by polymerized complex (PC) method and investigated for its physical and optical properties. The crystallization of CaFe2O4 made by PC method was found to occur in the temperature range of 700-1100 degrees C. The observation of highly pure phase and such lower crystallization tempearture in CaFe2O4 made by PC method, is in total contrast to that observed in CaFe2O4 prepared by the conventional solid-state reaction (SSR) method. The activation energy required for the growth of nanocrystalline CaFe2O4 in PC sample was found to be 8.4 kJ/mol. The band gap of nanocrystalline CaFe2O4 determined by UV-DRS was 1.91 eV (647 nm). The photocatalytic activity of PC materials for iso-propyl alcohol photodegradation under visible light (> or =420 nm) was much higher than that of SSR materials.

Prevalence of non-tuberculous mycobacteria in a hospital environment

In recent years, non-tuberculous mycobacteria (NTM) have emerged as an important cause of opportunistic nosocomial infections but there is little known about the isolation and identification of NTM in Korea. The aim of this study was to assess the prevalence of NTM in the hospital environment and identify the species. A total of 150 samples were collected from different parts of the hospital. NTM were isolated and identified by restriction fragment length polymorphism analysis of the gene encoding rpoB and partial sequencing analysis of hsp65 and rpoB. In this study, 60 strains of NTM were isolated from 50 of the 150 samples. Half of the tap water samples (50 of 100) were positive for mycobacteria. An estimated 73.3% of the isolates were saprophytic, 21.7% were potentially pathogenic and 5% were unidentified. The presence of NTM in hospital tap water is not uncommon. Such water isolates might cause true nosocomial infection in immunocompromised patients, in addition to the risk of false-positive culture results.