148 research outputs found
Study of the processing and properties of mixtures of recycled plastics for outdoor applications
There is an industrial need for the study of the mechanical and physical properties of recycled polyolefins mixed with cellulose fibres from diapers, wood and packaging containing aluminium. The recycling of thermoplastic based residues is economically very interesting for the easy reprocessing of these materials and flexible shaping using conventional moulding processes as injection moulding or intrusion.
Various mixtures of these materials were characterized in terms of their constituents and properties determined using 200 mm square mouldings of 10 mm and 5 mm thickness, in view of their potential application in urban furniture. These mouldings were processed by injection moulding and by intrusion that is a method which uses and extruder for delivering the melt directly into an injection mould. The mouldings were tested in terms of theirmechanical performance in impact and flexion.
The intrusion process yielded mouldings with properties similar to injection moulding but
appeared to be more attractive for requiring lower moulding pressure and thus lighter and
cheaper tooling.
The morphology of the mouldings, observed by bright field light microscopy showed some
contamination and voiding associated to specific processing conditions and moulding size, the thinner mouldings having less voids than the 10 mm thick. The higher voiding in the thicker mouldings was detrimental to the flexural and impact performances of the parts.
The coefficient of linear thermal expansion was determined and showed to be sensitive to the percentage of LDPE and fibres in the mixtures. The flexural stiffness of the moulded plates was assessed using the whole mouldings in the 3-point support test and showed the positive influence of the wood fibres and the diaper content in the mixtures. Conversely the impact performance assessed by the Charpy test was affected by the diaper content, but benefitted from the presence of aluminium from the recycled packaging.
The prediction of these properties using the law of mixtures for predicting the overall density in the mouldings was not particularly accurate for the mixtures with recycled diapers.European Commission for Education and Training, Erasmus placement scholarship at Hogeschool Gen
SISCLIMA : capitalisation de données agroclimatiques au Brésil
Dans le cadre de son système d'informations géographiques sur l'environnement en milieu rural (SISGEO), l'entreprise Brésilienne de Recherches Agronomiques (EMBRAPA) a mis au point un système de capitalisation d'informations agroclimatiques (SISCLIMA). Celui-ci a comme objectif la fourniture automatique des produits les plus classiques dans ce domaine (bulletin météorologique, calculs d'évapotranspiration, etc.), à partir des données brutes collectées sur une station météorologique. Le module comprend une vérification systématique détaillée des données saisies et leur correction, et fournit un fichier opérationnel des données élaborées au niveau journalier. Ce travail rend compte des critères climatologiques adoptés et des méthodes informatiques utilisées pour sa réalisation. (Résumé d'auteur
Better to light a candle than curse the darkness : illuminating spatial localization and temporal dynamics of rapid microbial growth in the rhizosphere
© The Author(s), 2013. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Frontiers in Plant Science 4 (2013): 323, doi:10.3389/fpls.2013.00323.The rhizosphere is a hotbed of microbial activity in ecosystems, fueled by carbon compounds from plant roots. Basic questions about the location and dynamics of plant-spurred microbial growth in the rhizosphere are difficult to answer with standard, destructive soil assays mixing a multitude of microbe-scale microenvironments in a single, often sieved, sample. Soil microbial biosensors designed with the luxCDABE reporter genes fused to a promoter of interest enable continuous imaging of the microbial perception of (and response to) environmental conditions in soil. We used the common soil bacterium Pseudomonas putida KT2440 as host to plasmid pZKH2 containing a fusion between the strong constitutive promoter nptII and luxCDABE (coding for light-emitting proteins) from Vibrio fischeri. Experiments in liquid media demonstrated that high light production by KT2440/pZKH2 was associated with rapid microbial growth supported by high carbon availability. We applied the biosensors in microcosms filled with non-sterile soil in which corn (Zea mays L.), black poplar (Populus nigra L.), or tomato (Solanum lycopersicum L.) was growing. We detected minimal light production from microbiosensors in the bulk soil, but biosensors reported continuously from around roots for as long as six days. For corn, peaks of luminescence were detected 1–4 and 20–35 mm along the root axis behind growing root tips, with the location of maximum light production moving farther back from the tip as root growth rate increased. For poplar, luminescence around mature roots increased and decreased on a coordinated diel rhythm, but was not bright near root tips. For tomato, luminescence was dynamic, but did not exhibit a diel rhythm, appearing in acropetal waves along roots. KT2440/pZKH2 revealed that root tips are not always the only, or even the dominant, hotspots for rhizosphere microbial growth, and carbon availability is highly variable in space and time around roots. - See more at: http://journal.frontiersin.org/Journal/10.3389/fpls.2013.00323/full#sthash.Bv7U0hD6.dpufNSF DEB Ecosystems grant #0415938 to Zoe G.Cardon and Daniel J. Gage, and an U.S. EPA Science to Achieve Results (STAR) Fellowship #91633901-0 to Patrick M. Herron
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MCNP neutron benchmarks
Over 50 neutron benchmark calculations have recently been completed as part of an ongoing program to validate the MCNP Monte Carlo radiation transport code. The new and significant aspects of this work are as follows: These calculations are the first attempt at a validation program for MCNP and the first official benchmarking of version 4 of the code. We believe the chosen set of benchmarks is a comprehensive set that may be useful for benchmarking other radiation transport codes and data libraries. These calculations provide insight into how well neutron transport calculations can be expected to model a wide variety of problems
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Identifying therapeutic drug targets using bidirectional effect genes.
Prioritizing genes for translation to therapeutics for common diseases has been challenging. Here, we propose an approach to identify drug targets with high probability of success by focusing on genes with both gain of function (GoF) and loss of function (LoF) mutations associated with opposing effects on phenotype (Bidirectional Effect Selected Targets, BEST). We find 98 BEST genes for a variety of indications. Drugs targeting those genes are 3.8-fold more likely to be approved than non-BEST genes. We focus on five genes (IGF1R, NPPC, NPR2, FGFR3, and SHOX) with evidence for bidirectional effects on stature. Rare protein-altering variants in those genes result in significantly increased risk for idiopathic short stature (ISS) (OR = 2.75, p = 3.99 × 10-8). Finally, using functional experiments, we demonstrate that adding an exogenous CNP analog (encoded by NPPC) rescues the phenotype, thus validating its potential as a therapeutic treatment for ISS. Our results show the value of looking for bidirectional effects to identify and validate drug targets
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