Biogenic synthesis of selenium nanoparticles by Shewanella sp. HN-41 using a modified bioelectrochemical system

BACKGROUND Synthesis of selenium nanoparticles from selenite by Shewanella sp. HN-41 demonstrated that particle size depended on the reaction time and biomass of cells. The slow reaction and low biomass tended to form small particles. In this study, Shewanella sp. HN-41 was introduced into the anode of a nonexternal circuit bioelectrochemical system (nec_BES) to convert chemical energy from lactate to low electron current to the cathode, where selenite was reduced. RESULTS Our experiment with two systems, one bioelectrochemical system with a cathode flushed with nitrogen and the other with a no-nitrogen-flushing cathode, showed that the former could not produce Se nanoparticles after 21 d, but the latter formed them with an average size of 37.7 nm. The SEM and TEM images demonstrated that the particle size of 10 nm occupied over 10% and most of the particles were in the range of 30­60 nm. The XRD result and SAED image demonstrated no clear peaks of crystal and proved that the Se nanoparticles are amorphous. CONCLUSIONS : The clean Se nanoparticles were synthesized and completely separated from bacterial cells in the bioelectrochemical system. This study opened a new approach for the biological synthesis of metal nanoparticles. Finally, the Se products in the range of 30­60 nm can be tested for antimicrobial activities in medical applications

Remarks on surfactant therapy in premature infants with respiratory distress syndrome at intensive care unit of Children Hospital No 2 from January 2007 to July 2007

Background: Respiratory distress is one among the leading reasons cause mortality for infants especially for preterm babies or light weight babies. Surfactant therapy in premature infants can decrease mortality, duration of respiratory treatment, pulmonary air leaks and chronic lung disease. Objective: This study aims to assess the effect of surfactant therapy in premature infants with respiratory distress syndrome at Intensive Care Unit of Children Hospital N\xb0.2. Subjects and method:A cases study about premature infants less than 24 hours after birth with respiratory distress syndrome (RDS) admitted to intensive care unit and treated with surfactant from January 2007 to July 2007 at the Children Hospital No 2. There were 30 cases recruited. The data was collected and analyzed by EpiInfo software 2002.Results: Most of them improved in respiration status after using surfactant (96.7%); no case of air leak was seen; 3 bronchopulmonary dysplasia cases and 4 deaths due to nosocomial infection were seen. Conclusion: Surfactant therapy was effective in premature infants with RDS. In the case of having economic advantages, surfactant may be indicated for preventive treatment on the premature and light weigh infants without respiratory distress syndrome on clinical aspect.