Osmotic dehydration kinetics of banana slices considering variable diffusivities and shrinkage

This article studied the use of diffusion models to describe variation of water quantity and sucrose quantity during osmotic dehydration of bananas cut into cylindrical slices. Bananas with radius of 1.7 cm and 18 °Brix (on average) were cut into 1.0 cm of thickness. A solution was proposed for the diffusion equation in cylindrical coordinates using the finite volume method, with fully implicit formulation. The diffusion equation was discretized assuming diffusivities and dimensions with variable values for the banana slices. Boundary conditions of the third kind have also been considered. The osmotic dehydration experiments were conducted in binary solutions (water and sucrose) under conditions of 40 and 60 °Brix and temperatures of 40 and 70°C. Mathematical modeling was proposed to describe the processes presented good results for water quantity and sucrose quantity, with good statistical indicators for all fits.     

Assessment of faecal pollution and relative algal abundances in Lakes Oconee and Sinclair, Georgia, USA

Water quality was assessed for five subregions of Lake Oconee and Lake Sinclair in Georgia, USA. The areas were chosen for their levels of human impact, including: (i) suburban development >30 years old; (ii) modern suburban development; (iii) industry; (iv) agriculture; and (v) an area of low human activity. The measured temperature, pH, dissolved oxygen concentration and turbidity values were normal for oligotrophic lakes. Faecal pollution in the lakes was determined using the membrane filtration method (Method 1600) on mEI plates for enterococci. There was a positive correlation between turbidity and the number of faecal enterococci in the lakes. The faecal pollution level was higher for the old suburban and agricultural areas. Faecal pollution in the agricultural region of Lake Oconee exceeded EPA regulatory standards. The faecal pollution source was identified using polymerase chain reaction detection, with Bifidobacterium adolescentis being a marker of human faecal pollution, and bovine-associated Bacteroides (BoBac) as a marker of cattle faecal pollution. Human faecal pollution was detected in the agricultural, old suburban and industrial areas of the lakes. In contrast, bovine faecal pollution was detected only in the agricultural area of Lake Oconee. Measurements of chlorophyll-a and relative algal community abundance indicated the least-impacted and modern suburban areas had significantly lower numbers of primary producers, being dominated by diatoms.     

Stable Blue Emission from a Polyfluorene/Layered‐Compound Guest/Host Nanocomposite

In this study a blue‐light‐emitting conjugated polymer, poly(9,9‐dioctylfluorene), is confined to the interlayer space of inorganic, layered metal dichalcogenide materials, metallic MoS₂, and semiconducting SnS₂. The nanocomposites are prepared through Li intercalation into the inorganic compound, exfoliation, and restacking in the presence of the polymer. X‐ray diffraction and optical absorption measurements indicate that a single conjugated polymer monolayer, with an overall extended planar morphology conformation, is isolated between the inorganic sheets, so that polymer aggregation or π–π interchain interactions are significantly reduced. Photoluminescence (PL) measurements show that the appearance of the undesirable green emission observed in pristine polymer films is suppressed by incorporating the polymer into the inorganic matrix. The blue emission of the intercalated polymer is stable for extended periods of time, over two years, under ambient conditions. Furthermore, the green emission is absent in the PL spectra of nanocomposite films heated at 100 °C for 7 h in air with direct excitation of the keto defect. Finally, no green emission was observed in the electroluminescence spectrum of light‐emitting devices fabricated with a polymer‐intercalated SnS₂ nanocomposite film. These results support the proposed hypothesis that fluorenone defects alone are insufficient to generate the green emission and that interchain interactions are also required.     

Evaluating Self-Generated Information: Anterior Prefrontal Contributions to Human Cognition.

The anterior or rostrolateral prefrontal cortex (RLPFC) is frequently recruited during complex cognitive tasks across a wide range of domains, including reasoning, long-term memory retrieval, and working memory. The authors report an event-related functional MRI study, indicating that the RLPFC is specifically involved in the evaluation of internally generated information--or information that cannot be readily perceived from the external environment but has to be inferred or self-generated. The findings are consistent with a hierarchical model of lateral prefrontal organization, with RLPFC contributing only at the highest orders of cognitive transformations. This characterization of RLPFC function may help explain seemingly disparate findings across multiple cognitive domains and could provide a unified account of this region's contribution to human cognition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)