Engineering thermoelectric and mechanical properties by nanoporosity in calcium cobaltate films from reactions of Ca(OH)2/Co3O4 multilayers.

Controlling nanoporosity to favorably alter multiple properties in layered crystalline inorganic thin films is a challenge. Here, we demonstrate that the thermoelectric and mechanical properties of Ca3Co4O9 films can be engineered through nanoporosity control by annealing multiple Ca(OH)2/Co3O4 reactant bilayers with characteristic bilayer thicknesses (b t ). Our results show that doubling b t , e.g., from 12 to 26 nm, more than triples the average pore size from ∼120 nm to ∼400 nm and increases the pore fraction from 3% to 17.1%. The higher porosity film exhibits not only a 50% higher electrical conductivity of σ ∼ 90 S cm-1 and a high Seebeck coefficient of α ∼ 135 µV K-1, but also a thermal conductivity as low as κ ∼ 0.87 W m-1 K-1. The nanoporous Ca3Co4O9 films exhibit greater mechanical compliance and resilience to bending than the bulk. These results indicate that annealing reactant multilayers with controlled thicknesses is an attractive way to engineer nanoporosity and realize mechanically flexible oxide-based thermoelectric materials.

Common etiologies of neonatal pleural effusion.

BACKGROUND: Pleural effusion is rare and includes several disease entities in the neonatal period. The aim of this study was to investigate the etiology, management, and outcome of neonatal pleural effusions. METHODS: We retrospectively collected all neonates who were admitted to the neonatal intensive care unit of Chung Shan Medical University Hospital, Taichung, Taiwan, with discharge diagnosis of pleural effusion, chylothorax, hydrothorax, hemothorax, and empyema, from January 1999 to December 2009. The characteristics, etiology, management, and outcome were analyzed. RESULTS: There were 21 patients identified, 16 males (76%) and 5 females (24%). Eight patients (38%) had primary and 13 patients (62%) had secondary etiologies. The etiologies included four parapneumonic effusions or empyema (19%); nine chylothorax (42.8%) with four congenital and five iatrogenic after thoracic surgery; three percutaneously inserted central venous catheter extravasation (14%); one umbilical venous catheter extravasation (4.7%); three hydrops fetalis (14%); and one congestive heart failure (4.7%). Fifteen patients (71%) needed chest tube placement. Conservative management with complete cessation of enteral feedings and use of total parenteral nutrition followed with infant formula containing medium-chain triglyceride was successful in six of the patients (67%) with chylothorax. There were two patients (22%) with chylothorax who received somatostatin administration; one was successful and the other one failed. Thoracic duct ligation was performed uneventfully in two patients with acquired chylothorax. There were three mortalities (14.3%) in this study, which were related to causes other than pleural effusion. CONCLUSIONS: Pleural effusions in the neonatal stage may result from chylothorax, hydrops fetalis, extravasation of percutaneously inserted central venous catheter, parapneumonic effusion, congestive heart failure, or other less frequently occurring conditions. Diagnostic chest tap is required for subsequent management. Good outcome is the rule except in hydrops fetalis, which carries high mortality rate.