Efficacy of waterborne polyurethane to prevent the enzymatic attack on paper‐based materials

The chemical and biological deterioration of paper‐based materials is mainly due to the degradation of its main component, the cellulose. However, paper also contains small amounts of organic and inorganic additives which might influence its biodegradability. To protect the paper‐based materials against various degradative agents, coating treatments with polymeric materials might be developed. In this study, the protective effect of commercial waterborne polyurethanes (WPU) against an enzymatic attack was investigated. Uncoated and coated samples with WPU of newsprint were subjected to degradation by enzymatic complexes (cellulosomes) produced by Clostridium cellulolyticum for different incubation times and then characterized using several analytical techniques (energy dispersive X‐ray fluorescence, scanning electron microscopy, nuclear magnetic resonance, Raman and infrared spectroscopy) with the aim to assess if waterborne polyurethanes can be used in paper conservation, looking at their efficacy against the biodegradation induced by enzymes. The selected waterborne polyurethanes showed a high effectiveness in the protection of paper‐based materials when they were submitted to the enzymatic attack. Indeed, their presence delayed the destruction of the cellulose matrix and the release of both soluble sugars and paper additives. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Prediction of thoracic injury severity in frontal impacts by selected anatomical morphomic variables through model-averaged logistic regression approach

This study resulted in a model-averaging methodology that predicts crash injury risk using vehicle, demographic, and morphomic variables and assesses the importance of individual predictors. The effectiveness of this methodology was illustrated through analysis of occupant chest injuries in frontal vehicle crashes.     

Chemical Signature and Reproductive Status in the Facultatively Polygynous ant Pachycondyla Verenae

In insects, cuticular hydrocarbons (CHCs) generally are used as cues and signals for within colony processes, such as signaling reproductive status, and between colony processes, such as colony membership. We examined CHC profiles of the facultatively polygynous ant Pachycondyla verenae in order to identify chemical signals of reproductive queens within colonies containing many gynes. Colonies of P. verenae, belonging to two different members of a complex of morphospecies, were collected from three geographic localities within South America. We also tested whether CHC profiles differed between geographic localities and morphospecies. We found three alkenes, two isomers of pentacosene and heptacosene, which were more abundant in CHC profiles of reproductive queens of this morphospecies complex. When we tested whether these differences were consistent across geographic localities, we found the abundance of these alkenes differed according to morphospecies, with the isomers of pentacosene being more abundant in queens from morph one, and heptacosene being more abundant in queens from morph two. Our study has given further insight into the mechanisms behind maintenance of reproductive dominance, and has demonstrated that chemical signatures associated with reproductive status in Pachycondyla verenae are not conserved within this species complex.     

Confirmation of E. coli among other thermotolerant coliform bacteria in paper mill effluents, wood chips screening rejects and paper sludges

Paper sludges are solid wastes material generated from the paper production, which have been characterized for their chemical contents. Some are rich in wood fiber and are a good carbon source, for example the primary and de-inking paper sludges. Others are made rich in nitrogen and phosphorus by pressing the activated sludge, resulting from the biological water treatments, with the primary sludge, yielding the combined paper sludge. Still, in the absence of sanitary effluents very few studies have addressed the characterization of their coliform microflora. Therefore, this study investigated the thermotolerant coliform population of one paper mill effluent and two paper mill sludges and wood chips screening rejects using chromogenic media. For the first series of analyses, the medium used was Colilert broth and positive tubes were selected to isolate bacteria in pure culture on MacConkey agar. In a second series of analyses, double selective media, based on ss-galactosidase and ss-glucuronidase activities, were used to isolate bacteria. First, the presence of thermotolerant coliforms was detected in low numbers in most water effluents, but showed that the entrance of the thermotolerant coliforms was early in the industrial process. Also, large numbers of thermotolerant coliforms, i.e., 7,000,000 MPN/g sludge (dry weight; d.w.), were found in combined sludges. From this first series of isolations, bacteria were purified on MacConkey medium and identified as Citrobacter freundii, Enterobacter sp, E. sakazakii, E. cloacae, Escherichia coli, K. pneumoniae, K. pneumoniae subsp. rhinoscleromatis, K. pneumoniae subsp. ozaenae, K. pneumoniae subsp. pneumoniae, Pantoea sp, Raoultella terrigena, R. planticola. Second, the presence of thermotolerant coliforms was measured at more than 3,700-6,000 MPN/g (d.w) sludge, whereas E. coli was detected from 730 to more than 3,300 MPN/g (d.w.) sludge. The presence of thermotolerant coliform bacteria and E. coli was sometimes detected from wood chips screening rejects in large quantities. Also, indigenous E. coli were able to multiply into the combined sludge, and inoculated E. coli isolates were often able to multiply in wood chips and combined sludge media. In this second series of isolations, API20E and Biolog identified most isolates as E. coli, but others remained unidentified. The sequences of the 16S rDNA confirmed that most isolates were likely E. coli, few Burkholderia spp, but 10% of the isolates remained unidentified. This study points out that the coliform bacteria are introduced by the wood chips in the water effluents, where they can survive throught the primary clarifier and regrow in combined sludges.     

Stability of Individual Phenolic Compounds and Antioxidant Activity During Storage of a Red Wine Powder

The addition of maltodextrin DE 10 to red wine (Cabernet Sauvignon) followed by freeze-drying allowed to obtain a free-flowing (dealcoholized) wine powder (WP) having a phenolic concentration about 3.6 times higher than the original liquid red wine. The powder, having a water activity (a _w) of 0.053 and 0.330 was stored at 28 °C and 38 °C and the content of ten different phenolic compounds was determined by HPLC. Caftaric acid, quercetin 3-glucoside, caffeic acid, gallic acid and resveratrol contents in the WP stored at 28 °C and 38 °C, remained almost constant during 70 days of storage, while epicatechin gallate, catechin, malvidin 3-G and epicatechin showed slight losses (about 15–25 %) during storage. On the contrary, epigallocatechin experienced a strong loss of concentration (around 61 % loss) during storage at the same conditions. A moderate decrease of antioxidant activity, determined by free radical scavenging capacity of the 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH*) and ferric reducing antioxidant power (FRAP) was observed along storage. This decrease was more important at higher temperature (38 °C) and higher a _w (0.33). These results would allow the feasibility of using this WP as a healthy ingredient in alcohol-free powder drinks.     

Et pourquoi pas une éducation aux sciences qui aborde la participation des acteurs sociaux aux controverses sociotechniques?

Résumé

Dans cet article nous faisons état d’une recherche qui s’est déroulée dans le cadre d’un projet orienté vers une éducation aux sciences citoyennes. Nous présentons la recherche et quelques-uns des résultats qui en sont issus, puis nous prenons position quant à la pertinence d’aborder, en classe de sciences, les questions de la participation citoyenne aux débats sociotechniques et des rôles et capacités des acteurs sociaux concernés.