1,915 research outputs found

    Water-like hierarchy of anomalies in a continuous spherical shouldered potential

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    We investigate by molecular dynamics simulations a continuous isotropic core-softened potential with attractive well in three dimensions, introduced by Franzese [cond-mat/0703681, to appear on Journal of Molecular Liquids], that displays liquid-liquid coexistence with a critical point and water-like density anomaly. Here we find diffusion and structural anomalies. These anomalies occur with the same hierarchy that characterizes water. Yet our analysis shows differences with respect to the water case. Therefore, many of the anomalous features of water could be present in isotropic systems with soft-core attractive potentials, such as colloids or liquid metals, consistent with recent experiments showing polyamorphism in metallic glasses.Comment: 27 pages, 9 figures. to appear in J. Chem. Phy

    Reproduction of blacknose shark (Carcharhinus acronotus) in coastal waters off northeastern Brazil

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    The blacknose shark, Carcharhinus acronotus, is a relatively small carcharinid, typically inhabiting continental shelf areas in the western Atlantic Ocean, from North Carolina throughout the Gulf of Mexico (Bigelow and Schroeder, 1948) and along the South American coast to Rio de Janeiro (Compagno, 1984). The abundance of this shark in nearshore areas throughout its distribution makes it accessible to commercial fishing, mainly from inshore hook-and-line and gill-net fisheries (Trent et al., 1997; Mattos and Hazin1)

    Influence of different protecting groups on the regioselectivity of the hydrotelluration reaction of hydroxy alkynes

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    The influence of protecting groups on the synthesis of regio- and stereodefined vinyl tellurides derived from the reaction of BuTeNa and propargylic- or homo-propargylic alcohols showed that TIPS silyl ether is useful as a regiodirecting group. The application of the methodology to the synthesis of a fragment of (±)-Seselidiol, a natural product, demonstrated the applicability of the new methodology

    Irreversible time-dependent rheological behavior of cement slurries : constitutive model and experiments

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    Over the last few decades, much focus has been given to investigating the reversible rheological behavior of thixotropic materials, but the description of the rheology of materials undergoing an irreversible process is still challenging. In this work, the time-dependent rheological behavior of a cement slurry is investigated. Different rheometric experiments are performed to evaluate the structure breakdown under shear, cement gelation, and curing process. A recently proposed thixotropic elasto-viscoplastic model [de Souza Mendes, Soft Matter 7, 2471-2483 (2011)] is modified to account for irreversible effects, which can be either of a chemical or physical nature, making the current model capable of describing reversible and irreversible processes with a single structure parameter. The parameters of the model are estimated from constant shear rate tests and from the flow curve of the fresh cement slurry. The model predictions are compared to step-down and step-up in stress experiments, and the results show that the model successfully describes experimental data obtained. Interesting phenomena are observed and discussed, including (i) thixotropic behavior during the dormant period, (ii) shear banding, (iii) irreversible changes in cement slurry rheology after the hydration reactions accelerate, and (iv) the existence of a characteristic time for the transition from a thixotropic-yield-stress material to a solid during curing. The predictive capability of the new model includes bifurcation, shear banding, stress overshoots, effects of chemical reactions, and irreversible shear degradation. It is argued that the ideas employed in the present work can be used to incorporate irreversible effects into other thixotropic models, giving rise to the possibility of describing the transient rheological behavior of complex materials in an unprecedented fashion. (c) 2019 The Society of Rheology

    Antihyperglycemic effect of casearia sylvestris leaves extract in streptozotocin induced diabetic rats

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    The antihyperglycaemic effect of Casearia sylvestris aqueous extract (CS) and its flavonoidic fraction using in vivo models in streptozotocin-induced diabetic rats was evaluated. CS (500 mg/kg) reduced blood glucose in rats three weeks after a single oral dose. The blood glucose significantly decreased in a test of tolerance to insulin. Phytochemical investigation on TLC, HPLC-DAD and NMR spectral analysis of extract and fractions confirmed the presence of flavonoids. These results direct the hypothesis that CS improves glucose metabolism by reducing insulin resistance, and it may be useful for the treatment of type 2 diabetes.Colegio de Farmacéuticos de la Provincia de Buenos Aire

    Antihyperglycemic effect of casearia sylvestris leaves extract in streptozotocin induced diabetic rats

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    The antihyperglycaemic effect of Casearia sylvestris aqueous extract (CS) and its flavonoidic fraction using in vivo models in streptozotocin-induced diabetic rats was evaluated. CS (500 mg/kg) reduced blood glucose in rats three weeks after a single oral dose. The blood glucose significantly decreased in a test of tolerance to insulin. Phytochemical investigation on TLC, HPLC-DAD and NMR spectral analysis of extract and fractions confirmed the presence of flavonoids. These results direct the hypothesis that CS improves glucose metabolism by reducing insulin resistance, and it may be useful for the treatment of type 2 diabetes.Colegio de Farmacéuticos de la Provincia de Buenos Aire

    Complex Network Tools to Understand the Behavior of Criminality in Urban Areas

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    Complex networks are nowadays employed in several applications. Modeling urban street networks is one of them, and in particular to analyze criminal aspects of a city. Several research groups have focused on such application, but until now, there is a lack of a well-defined methodology for employing complex networks in a whole crime analysis process, i.e. from data preparation to a deep analysis of criminal communities. Furthermore, the "toolset" available for those works is not complete enough, also lacking techniques to maintain up-to-date, complete crime datasets and proper assessment measures. In this sense, we propose a threefold methodology for employing complex networks in the detection of highly criminal areas within a city. Our methodology comprises three tasks: (i) Mapping of Urban Crimes; (ii) Criminal Community Identification; and (iii) Crime Analysis. Moreover, it provides a proper set of assessment measures for analyzing intrinsic criminality of communities, especially when considering different crime types. We show our methodology by applying it to a real crime dataset from the city of San Francisco - CA, USA. The results confirm its effectiveness to identify and analyze high criminality areas within a city. Hence, our contributions provide a basis for further developments on complex networks applied to crime analysis.Comment: 7 pages, 2 figures, 14th International Conference on Information Technology : New Generation
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