1,915 research outputs found
Water-like hierarchy of anomalies in a continuous spherical shouldered potential
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
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
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
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
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
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
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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