Characterisations of cassava starch and poly(butylene adipate-co-terephthalate) blown film with silicon dioxide nanocomposites

Films with high permeability are necessary for the packaging of agricultural products that respire to avoid anoxic conditions. This research developed and characterised bioplastic nanocomposite films with enhanced permeation and increased strength. Thermoplastic starch (TPS) was compounded with silicon dioxide (SiO₂) and blended with poly (butylene adipate-co-terephthalate) (PBAT) to produce bioplastic PBAT/TPS blend films via blown-film extrusion. Different SiO₂ contents (0.5%–1%) were dispersed in the matrices, causing interaction via hydrogen bonding with the TPS phase. SiO₂ at 1% significantly improved melting of the polymer blends, giving increasing amorphous ratios of the polymeric films. Microstructures and surface topography indicated voids between incompatible components and porous structures that improved permeation. Increasing SiO₂ content linearly enhanced oxygen and water vapour permeability by up to 39% and 16%, respectively. Tensile strength and elongation at break increased and decreased up to 40% and 32%, respectively, indicating increased rigidity due to adding solid nanoparticles to 1%. Migration phenomena of the film components, that is molecules with diol structures and silicon compounds depended on types of simulant and microstructures that induced swelling and release of the compounds. Film permeabilities increased, thereby facilitating air and humidity flow through the packaging.     

Persistent diarrhoea in children admitted to Port Moresby General Hospital

A retrospective study of the records of children admitted to Port Moresby General Hospital with diarrhoea during 1992 and 1993 was carried out to determine the morbidity, mortality and risk factors associated with persistent diarrhoea. 858 admissions of children under five years of age who had diarrhoea were identified from the ward admission registers, and case records for 724 were studied. Persistent diarrhoea occurred in 20%, and nearly half of these were in the 12-23 months age group. Children with persistent diarrhoea had a case fatality rate of 4.9%. Seasonality was similar for both persistent and non-persistent diarrhoea. In the crude analysis children of 12 months and older had a greater risk of developing persistent diarrhoea than those less than 12 months (odds ratio for children 12-23 months was 2.0 and for children 24-59 months 1.7; confidence intervals were 1.2-3.1 and 1.0-2.9 respectively); however, this difference was not found after logistic regression analysis. Poor nutritional status was a significant risk factor for persistent diarrhoea and remained so after controlling for confounding variables (odds ratio 2.7; confidence interval 1.8-4.0).