481 research outputs found

    Proposal of an inspection methodology for pneumatic drills

    Get PDF
    In recent years the contribution of pneumatic drills to the dispersion in the environment of insecticides particles derived from the abrasion of dressed seeds has been studied and different devices aimed at reducing the dust drift have been proposed. The European Directive 128/09 on the sustainable use of pesticides aims to achieve a more sustainable use of pesticides and introduces the compulsory inspection of equipment for pesticide application.At the present time, an official methodology to inspect both new and in use drills and the effectiveness of drift reducing devices is still lacking. The aim of the paper is to present a simplified methodology that can be applied to periodical inspection of the above mentioned equipment. Such a methodology has been elaborated basing on the results of a three-year activity, carried out at CRA-ING within the APENET research project

    Prediction of weld line location for injection molded thermoplastic components

    Get PDF
    Weld lines in polymeric injection molded parts occur wherever two or more melt fronts meet. They cause reduced mechanical properties and visual defects due to the poor intermolecular entanglement, molecular orientation induced by the fountain flow and the stress concentration effect of surface V-notch. A challenge related to these defects is that they are hard to detect and monitor because they’re usually not visible to the naked eye. Through this paper a numerical model for mold filling simulations has been developed aiming to predict the location of this defect and the initial meeting angle between the colliding flow fronts. A hybrid interface tracking technique was implemented in conjunction with a fix topology pseudo-quadratic mesh. Navier-Stokes equations were reduced to Hele-Shaw equations for thin plates. For validating purposes polypropylene plates injection moldings with weld lines were produced using a two-gated mold in a laboratory scale injector machine. Location of the defect was measure using an optical polariscope and then contrasted with simulation results. In order to establish the differences between 3D and Hele-Shaw models, predictions of weld line location were compared with the results provided by commercial injection molding simulation package Moldex3D.Publicado en: Mecánica Computacional vol. XXXV, no. 6Facultad de Ingenierí

    Prediction of weld line location for injection molded thermoplastic components

    Get PDF
    Weld lines in polymeric injection molded parts occur wherever two or more melt fronts meet. They cause reduced mechanical properties and visual defects due to the poor intermolecular entanglement, molecular orientation induced by the fountain flow and the stress concentration effect of surface V-notch. A challenge related to these defects is that they are hard to detect and monitor because they’re usually not visible to the naked eye. Through this paper a numerical model for mold filling simulations has been developed aiming to predict the location of this defect and the initial meeting angle between the colliding flow fronts. A hybrid interface tracking technique was implemented in conjunction with a fix topology pseudo-quadratic mesh. Navier-Stokes equations were reduced to Hele-Shaw equations for thin plates. For validating purposes polypropylene plates injection moldings with weld lines were produced using a two-gated mold in a laboratory scale injector machine. Location of the defect was measure using an optical polariscope and then contrasted with simulation results. In order to establish the differences between 3D and Hele-Shaw models, predictions of weld line location were compared with the results provided by commercial injection molding simulation package Moldex3D.Publicado en: Mecánica Computacional vol. XXXV, no. 6Facultad de Ingenierí

    Membrane cholesterol modulates LOX-1 shedding in endothelial cells

    Get PDF
    The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) is a scavenger receptor responsible for ox-LDL recognition, binding and internalization, which is up-regulated during atherogenesis. Its activation triggers endothelium dysfunction and induces inflammation. A soluble form of LOX-1 has been identified in the human blood and its presence considered a biomarker of cardiovascular diseases. We recently showed that cholesterol-lowering drugs inhibit ox-LDL binding and internalization, rescuing the ox-LDL induced apoptotic phenotype in primary endothelial cells. Here we have investigated the molecular bases of human LOX-1 shedding by metalloproteinases and the role of cell membrane cholesterol on the regulation of this event by modulating its level with MβCD and statins. We report that membrane cholesterol affects the release of different forms of LOX-1 in cells transiently and stably expressing human LOX-1 and in a human endothelial cell line (EA.hy926). In particular, our data show that i) cholesterol depletion triggers the release of LOX-1 in exosomes as a full-length transmembrane isoform and as a truncated ectodomain soluble fragment (sLOX-1); ii) endothelial cells secrete a soluble metalloproteinase which induces LOX-1 ectodomain shedding and iii) long term statins treatment enhances sLOX-1 proteolytic shedding

    Designing multiplayer games to facilitate emergent social behaviours online

    Get PDF
    This paper discusses an exploratory case study of the design of games that facilitate spontaneous social interaction and group behaviours among distributed individuals, based largely on symbolic presence 'state' changes. We present the principles guiding the design of our game environment: presence as a symbolic phenomenon, the importance of good visualization and the potential for spontaneous self-organization among groups of people. Our game environment, comprising a family of multiplayer 'bumper-car' style games, is described, followed by a discussion of lessons learned from observing users of the environment. Finally, we reconsider and extend our design principles in light of our observations

    Design of a novel LOX-1 receptor antagonist mimicking the natural substrate

    Get PDF
    The lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1), the major receptor for oxidized low-density lipoprotein (ox-LDL) in endothelial cells, is overexpressed in atherosclerotic lesions. LOX-1 specific inhibitors, urgently necessary to reduce the rate of atherosclerotic and inflammation processes, are not yet available. We have designed and synthesized a new modified oxidized phospholipid, named PLAzPC, which plays to small scale the ligand-receptor recognition scheme. Molecular docking simulations confirm that PLAzPC disables the hydrophobic component of the ox-LDL recognition domain and allows the interaction of the l-lysine backbone charged groups with the solvent and with the charged/polar residues located around the edges of the LOX-1 hydrophobic tunnel. Binding assays, in a cell model system expressing human LOX-1 receptors, confirm that PLAzPC markedly inhibits ox-LDL binding to LOX-1 with higher efficacy compared to previously identified inhibitors
    corecore