Interaction of silver nanoparticles with an environmentally beneficial bacterium, Pseudomonas chlororaphis

This study explores the potential antimicrobial mechanisms of commercial silver nanoparticles (Ag NPs) in the environmental bacterium, Pseudomonas chlororaphis O6. The 10nm size NPs aggregated in water, as demonstrated by atomic force microscopy. Solubility of the NPs at 10mg/L was 0.28 mg/L (pH 6) and 2.3mg/L (pH 7); release from 10mg/L bulk Ag was below detection. The NPs eliminated cell culturability at 3mg/L, whereas no effect was observed at 10mg/L bulk Ag. Zeta potential measurements revealed that the NPs were negatively charged; unlike Ag ions, their addition to the negatively charged cells did not change cell charge at pH 6, but showed a trend to reduce cell charge at pH 7. Isolated extracellular polymeric substances (EPS) from PcO6 was polydisperse, with negative charge that was neutralized by Ag ions, but not by the NPs. Addition of EPS eliminated Ag NP's toxicity in cells lacking EPS. Intracellular accumulation of OH was not detected in NP-treated cells; however, the use of scavengers suggested the NPs caused extracellular H(2)O(2) production. No evidence was found for loss of membrane integrity upon treatment with the NPs. Our findings indicate that growth of environmental bacteria could be impaired by Ag NPs, depending on the extent of EPS production.     

Misclassification of maternal smoking status and its effects on an epidemiologic study of pregnancy outcomes.

Reliance on self-reported smoking status among pregnant women can result in exposure misclassification. We used data from the Calcium for Preeclampsia Prevention trial, a randomized study of nulliparous women conducted from 1992 to 1995, to characterize tobacco exposure misclassification among women who reported at study enrollment that they had quit smoking. Urinary cotinine concentration was used to validate quit status, and factors associated with exposure misclassification and the effects of misclassification on associations between smoking and pregnancy outcomes were evaluated using logistic regression. Of 4,289 women enrolled, 508 were self-reported smokers and 771 were self-reported quitters. Of 737 self-reported quitters with a valid cotinine measurement, 21.6% had evidence of active smoking and were reclassified as smokers. Women who reported having quit smoking during pregnancy were more likely to be reclassified than women who reported quitting before pregnancy (p<.001). Among smokers, factors independently associated with misclassification of smoking status included fewer cigarettes smoked per day and fewer years smoked. After reclassification the odds ratio for a small-for-gestational-age birth among smokers decreased by 14%, and the smoking-related reduction in birth weight decreased by 15%. Effects of misclassification on the association with hypertensive disorders of pregnancy were present but less dramatic. In conclusion, use of self-reported smoking status collected at the time of study enrollment resulted in the introduction of bias into our study of smoking and pregnancy outcomes. The potential for this type of bias should be considered when conducting and interpreting epidemiologic studies of smoking and pregnancy outcomes.     

Functional properties of pasteurised liquid whole egg products as affected by the hygienic quality of the raw eggs

The viscosity, foaming and baking performances of pasteurised liquid whole egg products were investigated to study the influence of raw egg hygienic quality on egg product functional performances. Uracil, lactic acid and 3OH-butyric acid measured in the pasteurised egg products were taken as chemical indices of the hygienic quality of the raw material. A high variability in the functional properties was observed, especially for overrun and foam stability, as well as in the chemical indices of hygiene. Many interesting correlations were found between variables, for example between overrun and cake volume (p < 0.001). Instead, no significant correlations were found between the chemical indices and the different functional properties. However, the application of Principal Component Analysis demonstrated that a good hygienic quality of the raw material used to prepare the liquid whole egg products is a prerequisite needed to develop good functional performances, although other factors pertaining to composition or processing also have a role.     

Socially Conscious Decision-Making

For individually motivated agents to work collaboratively to satisfy shared goals, they must make decisions about actions and intentions that take into account their commitments to group activities. This paper examines the role of social consciousness in the process of reconciling intentions to do group-related actions with other, conflicting intentions. We operationalize the notion of social consciousness and provide a first attempt to formally add social consciousness to a cooperative decision-making model. We define a measure of social consciousness; describe its incorporation into the SPIRE experimental system, a simulation environment that allows the process of intention reconciliation in team contexts to be studied; and present results of several experiments that investigate the interaction in decision-making of measures of group and individual good. In particular, we investigate the effect of varying levels of social consciousness on the utility of the group and the individuals it comprises. A key finding is that an intermediate level of social consciousness yields better results in certain circumstances than an extreme commitment. We suggest preliminary principles for designers of collaborative agents based on the results.     

Mechanical,thermal, and flame-retardant performance of polyamide 11–halloysite nanotube nanocomposites

This study focused on the influence of different filler loadings on the elongation at break and flammability properties of the PA11/FR/HNTs nanocomposites. Polyamide 11 (PA11)/flame-retardant (FR) additives/halloysite nanotubes (HNTs) nanocomposites were melt compounded via twin-screw extrusion for all the compositions. Three FR additive loadings (15, 20, and 25 wt%) and three HNTs loadings (2.5, 5, and 10 wt%) were selected. The formula with 25 % FR and 2.5 % HNT had the lowest additives content and the highest elongation at break of 10.22 % among all UL-94 V-0 rated formulas. A homogeneous dispersion of HNTs in PA11 matrix was observed by transmission electron microscopy. Differential scanning calorimeter measurements indicated that HNTs behaved as nucleating agents by accelerating the rate of crystallization, thus increasing crystallization temperature. The young’s modulus of the PA11 nanocomposites was enhanced with the addition of HNTs. Micro-scale combustion calorimeter results demonstrated that the addition of HNTs also decreased the peak heat release rate of the nanocomposites. These results indicate the effectiveness of HNTs on the mechanical, thermal, and flame-retardant performance of PA11/FR/HNTs nanocomposites.     

Contemplation of moral dilemmas eliminates sex differences on the iowa gambling task.

Men outperform women on the Iowa Gambling Task (IGT; A. Bechara, H. Damasio, D. Tranel, & A. R. Damasio, 1997). In this study, the authors show that sex differences are not due to differences in general emotional arousal or the abilities to calculate or reverse responses. Imaging studies have shown that, during the IGT, men increase activity in the right dorsolateral prefrontal cortex (PFC) and lateral orbital PFC, whereas women increase activity in the left medial orbital PFC. Deliberation of personal moral (PM) dilemmas also increases activity in medial and lateral dorsal PFC, whereas deliberation of moral impersonal (MI) dilemmas increases activity in lateral dorsal PFC. In the present study, men and women performed the IGT during PM, MI, or control deliberations. Deliberation of only PM dilemmas increased women's IGT performance to the level of men. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attending to others’ posts in asynchronous discussions: Learners’ online “listening” and its relationship to speaking

Theoretical models of collaborative learning through online discussions presuppose that students generally attend to others’ posts. However, a succession of studies over the last decade has shown this assumption to be unwarranted. Instead, research indicates that learners attend to others’ posts in diverse and particular ways—an activity we have conceptualized as online “listening.” In this study, we take an important step forward in developing a robust theory of online listening by examining the relationship between how learners “listen” (access existing posts) and “speak” (contribute posts) in online discussions. Ten variables indexing four dimensions of students’ listening (breadth, depth, temporal contiguity and revisitation) and five variables indexing three dimensions of students’ speaking (discursiveness, depth of content and reflectivity) were calculated for 31 students participating in 6 week-long online discussions as part of an undergraduate educational psychology course. Multi-level mixed-model linear regressions indicated that responsiveness of students’ posts was positively predicted by how often they revisited previously read peer posts, and negatively related to a greater number of posts in the discussion overall. The depth of posts’ contents was predicted by the percentage of posts viewed that students actually read (as opposed to scanned). An exploratory follow-up analysis indicated that these listening-speaking relationships manifest differently over time for distinct subsets of learners (e.g., a decrease in variable pairs versus corresponding fluctuations around stable levels). Put together, results suggest that when students take the time to read and re-read their peers’ posts there are related benefits in the quality of the posts they contribute.     

Sweet temptation: Effects of exposure to chocolate-scented lotion on food intake

Food-scented products are widely available, yet it is unclear whether they influence eating behavior. Food-related cues can increase intake; therefore, it was anticipated that conscious exposure to food-scented products (e.g., body lotion) could also influence consumption. Female participants (n = 58) were randomly assigned to an exposure condition (labeled chocolate lotion, unlabeled chocolate lotion, or unscented lotion), and their subsequent intake of chocolate-chip cookies was measured. A significant effect of condition on intake emerged. Those who knew that they were evaluating a chocolate-scented lotion ate more than did those exposed to the same (unlabeled) lotion, suggesting that conscious exposure to chocolate-related products may increase food intake.