426 research outputs found

    Electrical conductance of hydrogen chloride in dimethylsulphoxide at 25°C

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    The electrical conductance of hydrogen chloride solutions in DMSO at 25°C has been studied. The limiting molar conductance is 38·7 int mho cm2 int mho cm2/mol. Conductivity data were interpreted with the Fuoss' theory for associated 1-1 type electrolytes. The association constant related to pair formation is 115·7 l/mol. The mechanism of electricl conduction of HCl in DMSO at infinite dilution resembles that of other 1-1 type electrolytes in the same solvent, in which charges are transported by simple entities in a viscous continuum.On a étudié la conductivité électrique des solutions de chlorure d'hydrogéne dans le DMSO à 25°C. La conductivité limite molare est de 38,7 mho int cm2/mol. Les données expŕimentalles de la conductivité furent interprétées d'aprés la théorie de Fuoss pour des électrolytes associé du type 1-1. La constante d'association liée à la formation de paires ioniques simple est 115,7 l/mol. Le mechanisme de la conduction électrique du HCl dans le DMSO à dilution infinie ressemble celui des autres électrolytes du type 1-1 dans le même dissulvant, puisque les charges sont transportées par des entités simples dans un milieu visqueux continu.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

    Multifractal analysis of vertical total electron content (VTEC) at equatorial region and low latitude, during low solar activity

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    This paper analyses the multifractal aspects of the GPS data (measured during a period of low solar activity) obtained from two Brazilian stations: Belém (01.3° S, 48.3° W) and São José dos Campos (SJC) (23.2° S, 45.9° W). The results show that the respective geographic sites show important scaling differences as well as similarities when their multifractal signatures for vertical total electron content (VTEC) are compared. The <I>f</I>(&alpha;) spectra have a narrow shape for great scales, which indicates the predominance of deterministic phenomena, such as solar rotation (27 days) over intermittent phenomena. Furthermore, the <I>f</I>(&alpha;) spectra for both sites have a strong multifractality degree at small scales. This strong multifractality degree observed at small scales (1 to 12 h) at both sites is because the ionosphere over Brazil is a non-equilibrium system. The differences found were that Belém presented a stronger multifractality at small scales (1 h to 12 h) compared with SJC, particularly in 2006. The reason for this behaviour may be associated with the location of Belém, near the geomagnetic equator, where at this location the actions of X-rays, ultraviolet, and another wavelength from the Sun are more direct, strong, and constant throughout the whole year. Although the SJC site is near ionospheric equatorial anomaly (IEA) peaks, this interpretation could explain the higher values found for the intermittent parameter μ for Belém compared with SJC. Belém also showed the presence of one or two flattening regions for <I>f</I>(&alpha;) spectra at the same scales mentioned before. These differences and similarities also were interpreted in terms of the IEA content, where this phenomenon is an important source of intermittence due the presence of the VTEC peaks at ±20° geomagnetic latitudes

    Effect of temperature on the electrical conductance of hydrogen chloride in dimethylsulphoxide

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    The electrical conductance of solutions of hydrogen chloride in dimethylsulphoxide at temperature from 25 to 45°C has been studied. Results have been interpreted with the Fouss theory for associated 1-1 type electrolytes. Values of the association constant KA and the J parameter have been computed at each temperature. The temperature dependence of the molar conductance is inferred from the theoretical equation and related to the temperature dependence of viscosity.La conductance électrique des solutions de chlorure d'hydrogène dans le diméthylsulfoxyde à des températures de 25 a 45°C a été étudiée. Les résultats ont et́é inteprétés par la théorie de Fuoss pour de electrolytes associées du type 1-1. Les valeurs de la constante d'association KA et du paramètre J ont été calculées à chaque température. La dépendance de la conductivité molare avec la température est déduite de l'équation théorique et référée a la dépendance de la viscosité avec la température.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

    Efeito de hospedeiros e temperaturas na biologia de Anastrepha grandis (Macquart, 1846) (Diptera: Tephritidae) e comprovação em campo, do modelo de exigências térmicas obtido em laboratório.

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    Dissertação (Mestrado). Mestre em Entomologia, Programa de Pós-Graduação em Entomologia, Instituto de Biologia, Universidade Federal de Pelotas, 2014. Orientador Dori Edison Nava (CPACT); co-orientador Flávio Roberto Mello Garcia

    Biologia de Anastrepha grandis (Macquart, 1846) (Diptera: Tephritidae) sob diferentes temperaturas.

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    O trabalho teve como objetivo estudar o efeito de temperaturas constantes sobre a biologia de adultos de A. grandis

    Ocupação de manchas florestais no Pantanal por duas espécies de roedores: Clyomys laticeps e Thrichomys pachyurus.

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    A fragmentação e a perda de habitat afetam de diferentes maneiras as comunidades biológicas. os efeitos variam muito de espécie para espécie, com algumas sendo extintas enquanto outras são beneficiadas. Tendo em vista o mosaico vegetacional que caracteriza a paisagem no Pantanal, o presente estudo relacionou o tamanho e o isolamento médio das manchas florestais à probabilidade de ocupação por duas espécies de roedores: Clyomys laticeps (Thomas, 1841) e Thrichomys pachyurus (Wagner, 1845)

    Development of Anastrepha grandis (Diptera: Tephritidae) under constant temperatures and field validation of a laboratory model for temperature requirements.

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