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Showing papers by "University of Extremadura published in 1980"


Journal ArticleDOI
TL;DR: A general formalism for calculating translational and rotational transport properties, as well as intrinsic viscosities, of rigid macromolecules with an arbitrary shape is proposed in this paper, which can be regarded as a generalization of the one proposed by Nakajima and Wada.
Abstract: A general formalism, which includes translation–rotation coupling, is proposed for calculating translational and rotational transport properties, as well as intrinsic viscosities, of rigid macromolecules with an arbitrary shape. This formalism is based on Brenner's theory of translational–rotational dynamics and on methods for the calculation of hydrodynamic properties that have been already presented, and can be regarded as a generalization of the one proposed by Nakajima and Wada. The calculated transport properties depend on the origin as predicted by Brenner's theory, but in a disagreement with him, the center of resistance and the center of diffusion do not coincide. As one can define several hydrodynamic centers, which in practice turn out to be located at different points, the influence of the choice of the center on the calculated transport properties is discussed. An analysis of the translation–rotation coupling effects in translational diffusion reveals that they arise exclusively from hydrodynamic interactions and are rather small in some cases of interest. Finally, we present a study of the rotational diffusion of rigid bent rods with a fixed length-to-diameter ratio. The diffusion coefficients obtained can be useful to estimate changes with respect to a straight rod.

85 citations


Journal ArticleDOI
01 Jun 1980-Talanta
TL;DR: A new spectrophotometric method is proposed for differentiating mononuclear and polynuclear complexes as well as for determining the extraction constant K*(e) of any complex A(m)B(n), based on the effect of dilution on the degree of dissociation of the complex.

18 citations


Journal ArticleDOI
TL;DR: In this paper, the polyhydroxyalkyl chain of 6,6-dimethyl-2-(d -gluco -pentitol-l-yl)-4,5,6,7-tetrahydroindol-4-one and 2-( d - galacto-pentitol l-yl)4, 5, 6,7, 7, 7 -tetrahedron 4-one were obtained by acid-catalysed dehydration.

14 citations


Journal ArticleDOI
TL;DR: In this paper, the reaction between 2-amino-2-deoxyaldoses and β-dicarbonyl compounds yields polyhydroxyalkylpyrroles.

13 citations


Journal ArticleDOI
TL;DR: In this article, a simple and general expression for the first derivative of the intermediate scattering function at short times is derived from the Rouse-Zimm matrix formalism for flexible chains in solution.

5 citations


09 Dec 1980
TL;DR: Garcia-Gallo et al. as discussed by the authors argue that no es posible concebir una ciudad medieval como una contemporanea, aleging no serconcelo.
Abstract: El profesor Garcia-Gallo indica, al comparar el posible esquema2 de los municipios medievales con los de otros tiempos, que no cabehablar de autonomia o descentializaci6n, como hoy se harfa, . .paca ex-plicar su vida propia y en ciertos aspectos independiente ` . No es posible concebir una ciudad medieval como una contemporanea. Ni aurt. . en plena Edad Media asimilar ciudades como Soria, integrada por urr: nucleo de nobles asentados en la misma y encargados de su gobiernoy defensa, con Ciudad Rodrigo, formada por 'una comunidad de cl6rigos y otra de vecinos, o con Madrid, constituida en concejo donde pobres y ricos quedan equiparados . Ya en el siglo xlv, cuando el concejoconstituye un tipo de estructura y organizacibn local, la ciudad de Toledo se opone a ser considerada como uno de ellos, alegando no serconcelo. Pero si es posible hater menci6n a la fuerte personalidad que en lossiglos xllc y xIV apuntaron las ciudades, villas y lugares en tanto poscian una organization municipal independiente y jurisdiction sobre un determinado territorio, idea que en los documentos de la epoca se expresa con la palabra concejo 2 .

3 citations


Journal ArticleDOI
TL;DR: In this paper, a spectrofluorometric study was made of the complex 1,4-diaminoanthraquinone-Ca in aqueous sulfuric mediums [λmax,ex = 410 nm; λmax,em = 580 nm; 50% H2O; stable for at least 4 hr; range temperature optimum = 20-35 °C; [R]optimum = 2 × 10−4M; stoichiometry 2:1 (fluorescent complex) and 1:1(no fluorescent complex).

2 citations



Journal ArticleDOI
TL;DR: In this paper, the influence of pH on the absorption spectra of 1,2,7-trihydroxyanthraquinone in different aqueous alcoholic solutions was investigated.

1 citations