152 research outputs found

    Modeling the rheological properties of highly nano-filled polymers

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    Organic and inorganic materials are usually added to polymers in order to achieve some benefits such as reducing the product cost, as well as achieving higher modulus and strength. Addition of these materials would change polymers’ behavior. Adding nano-materials to polymers on the other hand is a new challenge in the field of polymer composites where previous studies were unable to achieve good correlation with nano-composites at higher particle volume fractions. In this research, Yamamoto network theory is developed to investigate the behavior of highly nano-filled systems. For this purpose, five different types of sub-chain and two types of junctions are considered and the effect of particle size, concentration, and the model parameters in association with the behavior of the junctions are studied. Moreover, some experiments are performed on polystyrene filled with nano-silica at different particle size and concentration values in frequency mod in the linear region. At last, we compared the results of our final model with the experiments in order to evaluate its accuracy, which confirmed a very good agreement. © 2016, © The Author(s) 2016

    Symbolic Versus Numerical Computation and Visualization of Parameter Regions for Multistationarity of Biological Networks

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    We investigate models of the mitogenactivated protein kinases (MAPK) network, with the aim of determining where in parameter space there exist multiple positive steady states. We build on recent progress which combines various symbolic computation methods for mixed systems of equalities and inequalities. We demonstrate that those techniques benefit tremendously from a newly implemented graph theoretical symbolic preprocessing method. We compare computation times and quality of results of numerical continuation methods with our symbolic approach before and after the application of our preprocessing.Comment: Accepted into Proc. CASC 201

    Self-Assembled Molecular-Electronic Films Controlled by Room Temperature Quantum Interference

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    If single-molecule, room-temperature, quantum interference (QI) effects could be translated into massively parallel arrays of molecules located between planar electrodes, QI-controlled molecular transistors would become available as building blocks for future electronic devices. Here, we demonstrate unequivocal signatures of room-temperature QI in vertical tunneling transistors, formed from self-assembled monolayers (SAMs), with stable room-temperature switching operations. As a result of constructive QI effects, the conductances of the junctions formed from anthanthrene-based molecules with two different connectivities differ by a factor of 34, which can further increase to 173 by controlling the molecule-electrode interface with different terminal groups. Field-effect control is achieved using an ionic liquid gate, whose strong vertical electric field penetrates through the graphene layer and tunes the energy levels of the SAMs. The resulting room-temperature on-off current ratio of the lowest-conductance SAMs can reach up to 306, about one order of magnitude higher than that of the highest-conductance SAMs

    Functional definition of a transcription factor hierarchy regulating T cell lineage commitment

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    T cell factor 1 (Tcf1) is the first T cell-specific protein induced by Notch signaling in the thymus, leading to the activation of two major target genes, Gata3 and Bcl11b. Tcf1 deficiency results in partial arrests in T cell development, high apoptosis, and increased development of B and myeloid cells. Phenotypically, seemingly fully T cell-committed thymocytes with Tcf1 deficiency have promiscuous gene expression and an altered epigenetic profile and can dedifferentiate into more immature thymocytes and non-T cells. Restoring Bcl11b expression in Tcf1-deficient cells rescues T cell development but does not strongly suppress the development of non-T cells; in contrast, expressing Gata3 suppresses their development but does not rescue T cell development. Thus, T cell development is controlled by a minimal transcription factor network involving Notch signaling, Tcf1, and the subsequent division of labor between Bcl11b and Gata3, thereby ensuring a properly regulated T cell gene expression program.Molecular Technology and Informatics for Personalised Medicine and Healt

    Pancreatitis in RYR1-related disorders

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    Mutations in RYR1 encoding the ryanodine receptor (RyR) skeletal muscle isoform (RyR1) are a common cause of inherited neuromuscular disorders. Despite its expression in a wide range of tissues, non-skeletal muscle manifestations associated with RYR1 mutations have only been rarely reported. Here, we report three patients with a diagnosis of Central Core Disease (CCD), King-Denborough Syndrome (KDS) and Malignant Hyperthermia Susceptibility (MHS), respectively, who in addition to their (putative) RYR1-related disorder also developed symptoms and signs of acute pancreatitis. In two patients, episodes were recurrent, with severe multisystem involvement and sequelae. RyR1-mediated calcium signalling plays an important role in normal pancreatic function but has also been critically implicated in the pathophysiology of acute pancreatitis, particularly in bile acid- and ethanol-induced forms. Findings from relevant animal models indicate that pancreatic damage in these conditions may be ameliorated through administration of the specific RyR1 antagonist dantrolene and other compounds modifying pancreatic metabolism including calcium signalling. These observations suggest that patients with RYR1 gain-of-function variants may be at increased risk of developing acute pancreatitis, a condition which should therefore be considered in the health surveillance of such individuals
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