Una aproximación estadística al estudio de la carbonatación del hormigón

Carbonation is one of the factors that conditions reinforced concrete durability, while porosity is one of the parameters that determines the carbonation rate: as a rule, the greater the porosity, the higher the rate. While many papers have been published on the effect of CO2 penetration in the pore solutions of concretes prepared under different experimental conditions, the literature has yet to address the joint effect of the factors considered in concrete design, such as the water/cement (w/c) ratio, type of cement, type of aggregate and presence of admixtures. The present paper discusses the findings of a statistical study of the impact of the aforementioned factors on both system porosity and carbonation rate. The type of cement, individually and in its interaction with the rest of the factors, proved to be the major determinant in concrete carbonation.La carbonatación es uno de los factores que supedita la durabilidad del hormigón armado, siendo la porosidad uno de los parámetros que más condicionan la velocidad de carbonatación. Son muchos los trabajos que estudian el efecto de la penetración del CO2 en la solución de los poros de hormigones preparados bajo distintas condiciones experimentales, sin embargo, no se encuentran referencias que analicen de forma conjunta el efecto de ciertos factores como son la relación agua/cemento (a/c ratio), el tipo de cemento, el tipo de árido y la presencia de aditivos, normalmente consideradas a la hora de diseñar un hormigón. En este trabajo se discuten los resultados obtenidos tras realizar un estudio estadístico del efecto que tienen los factores previamente mencionados, tanto en la porosidad de estos sistemas como en su nivel de carbonatación. El cemento tanto de manera individual como en sus interacciones con el resto de los factores es el factor que mas afecta a la carbonatación del hormigón

Heteroaromatic alanine derivatives bearing (oligo)thiophene units : synthesis and photophysical properties

A series of new benzoxazolylalanine derivatives bearing (oligo)thiophene units at the side chain were synthesized in good yields. The photophysical characterization of these amino acids was performed by UV-vis absorption and fluorescence emission studies and revealed that some of the compounds display high fluorescent quantum yields, making them good candidates for application as fluorescent probes.Fundação para a Ciência e Tecnologia (FCT) - PTDC/QUI/66250/2006, bolsa de doutoramento SFRH/BD/35905/2007 atribuída a E. Oliveir

El complejo de Órdenes: subdivisión, descripción y discusión sobre su origen.

[Resumen] El Complejo de Ordenes, el mayor de los macizos alóctonos con rocas máficas y ultramAficas de Galicia y el N de Portugal, se ha subdividido en cinco unidades en base, fundamentalmente, a las asociaciones litológicas: U. de Santiago, U. de Villa de Cruces, U. De la Sierra del Careón-Bazar, U. de SobradoMellid y U. de Betanzos-Arzúa. Todas ellas están separadas entre si por cabalgamientos y superpuestas tectónicamente. Para cada unidad, se realiza una descripción petrológica y se analizan las relaciones de las diferentes rocas entre si. ,Se efectúa, además, una revisión de los datos geoquimicos disponibles y, finalmente, se discute el origen probable de las distintas unidades[Abstract] The Ordenes Complex, the biggest OI the allochthonous massifs with mafic and ultramafic rocks in Galicia and northern Portugal, has been divided into five units according to the lithological associations: Santiago Unit, Villa de Cruces Unít, Sierra del Care6n-Bazar Unit, Sobrado-Mellid Unít and BetanzoS-Arzúa Unít. They are separated from each other by thrust faults and tectonically stacked. For each OI the units, a petrological description is given, explaining the relationships between the different rock types. Moreover, the geochemical data available are reviewed and the probable origin of the units is discusse

Imidazo-benzo-15-crown-5 ether bearing arylthienyl and bithienyl moieties as novel fluorescent chemosensors for Pd2+ and Cu2+

Novel fluorescent ionophores bearing imidazo-arylthienyl or imidazo-bithienyl pi-conjugated bridges functionalized with one or two fused benzo-15-crown-5 ethers as receptor units are reported. The sensing ability of the compounds in the presence of metallic cations (Li+, Na+, K+, Ca2+, Zn2+, Cu2+, Ni2+, Pd2+ and Hg2+) and fluoride ion was studied in MeCN/DMSO solutions by absorption and emission spectroscopy. The experimental results indicate that all compounds could act as selective fluorimetric sensors for Cu2+ and Pd2+ and also for the fluoride ion, in the case of the bis-substituted crown ether derivatives.Fundação para a Ciência e a Tecnologia (FCT) - PTDC/QUI/66250/2006 (FCOMP-01-0124-FEDER-007428), SFRH/BD/36396/200

Exploring the emissive properties of new azacrown compounds bearing aryl, furyl or thienyl moieties: a special case of chelation enhancement of fluorescence upon interaction with Ca2+, Cu2+ or Ni2+

Three new compounds bearing furyl, aryl or thienyl moieties linked to an imidazo-crown ether system (1, 2 and 3) were synthesized and fully characterized by elemental analysis, infrared, absorption and emission spectroscopy, X-ray crystal diffraction, and MALDI-TOF-MS spectrometry. The interaction towards metal ions (Ca2+, Cu2+, Ni2+ and Hg2+) and F- has been explored in solution by absorption and fluorescence spectroscopy. Mononuclear and binuclear metal complexes using Cu2+ or Hg2+ as metal centers have been synthesized and characterized. Compounds 2 and 3 show a noticeable enhancement of the fluorescence intensity in the presence of Ca2+ and Cu2+ ions. Moreover compound 3 presents a dual sensory detection way by the modification of the fluorimetric and colorimetric properties in the presence of Cu2+ or Hg2+. The EPR studies in frozen solution and in microcrystalline state of the dinuclear Cu(II)2 complex revealed the presence of an unique Cu2+ type.Fundação para a Ciência e a Tecnologia (FCT)We are indebted to InOU Uvigo by project K914 122P 64702 (Spain) and FCT-Portugal by project PTDC/QUI/66250/2006 for financial support. The NMR spectrometers are part of the National NMR Network and were purchased in the framework of the National Programme for Scientific Re-equipment, contract REDE/1517/RMN/2005, with funds from POCI 2010 (FEDER) and FCT-Portugal. C.L. thanks Xunta de Galicia, Spain, for the Isidro Parga Pondal Research Program. E.O. and R.B. thank FC-MCTES (Portugal) by their PhD grants SFRH/BD/35905/2007 and SFRH/BD/36396/2007, respectively. We are gratefull to Dr. Cristina Nunez and Dr. Pablo Gonzalez from the REQUIMTE, Universidade NOVA de Lisboa, Portugal, for their important help with the crystallographic and EPR data, respectively, and Dr. Jose Luis Capelo from the University of Vigo, Spain, for the help with the MALDI-TOF-MS spectra

Synthesis and characterization of novel (oligo)thienyl-imidazo-phenanthrolines as versatile π-conjugated systems for several optical applications

A series of new heterocyclic chromophores 3-6 were synthesised in moderate to excellent yields by condensation of 5,6-phenantroline-dione with formyl-thiophene derivatives 1-2 in the presence of ammonium acetate in glacial acetic acid. These chromophores possess a (oligo)thienyl- π-conjugated system attached to an imidazophenanthroline moiety. These derivatives were evaluated concerning their solvatochromic properties, thermal stabilities and molecular optical nonlinearities.Fundação para a Ciência e Tecnologia (FCT) - projecto PTDC/QUI/66250/2006, bolsa de doutoramento a R.M.F. Batista SFRH/BD/36396/2007), (FCT-UNL) REQUIMTE

Synthesis and evaluation of bipendant-armed (oligo)thiophene crown ether derivatives as new chemical sensors

Three new (oligo)thiophene bipendant-armed ligands 2a-c, derived from 2-(aminomethyl)-15-crown-5, have been synthesized and characterized. Compounds 2a-c were prepared by reductive amination of the corresponding macrocycle with formyl thiophene derivatives 1a-c in the presence of NaBH(OAc)3 in fair to good yields. The photophysical properties of ligands 2a-c were studied and they were also evaluated as chemosensors in the presence of Na(I), Ag(I), Pd(II) and Hg(II) cations in acetonitrile solution.Fundação para a Ciência e a Tecnologia (FCT

Influence of colloid suspensions of humic acids on the alkaline hydrolysis of N-methyl-N-nitroso-p-toluene sulfonamide

The influence of humic substances (HSs) upon the alkaline hydrolysis of N-methyl-N-nitroso-p-toluene sulfonamide has been studied. Important inhibition of hydrolysis reaction has been reported. This inhibition has been explained in terms of association of reactants to the humic substances. Kinetic results have been modeled using the micellar pseudophase model. © 2010 Wiley Periodicals, Inc.Fil: Astray, G.. Universidad de Vigo; EspañaFil: García Río, L.. Universidad de Santiago de Compostela; EspañaFil: Lodeiro, Anibal. Universidad de Vigo; EspañaFil: Mejuto, Juan Carlos. Universidad de Vigo; EspañaFil: Moldes, O.. Universidad de Vigo; EspañaFil: Morales, J.. Universidad de Vigo; EspañaFil: Moyano, Fernando. Universidad de Vigo; España. Universidad Nacional de Río Cuarto. Instituto para el Desarrollo Agroindustrial y de la Salud. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto para el Desarrollo Agroindustrial y de la Salud; Argentin

A Revision of the characteristics and clasification of the hercynian granitoids of Northern Galicia and Western Asturias (NW Spain)

[Resumen] Este trabajo resume parte de los resultados obtenidos en el desarrollo del proyecto «Caracterización y correlación petrológica, geoquímica y geocronológica de las rocas graníticas de Galicia (A Coruña-Lugo)>>, realizado por el 1. ~G. M. E. El estudio sistemático de los distintos plutones graníticos de esta región ha puesto de manifiesto que los criterios de clasificación tradicionalmente utilizados en este ámbito geológico, presentan una serie de limitaciones debidas por una parte a la rigidez de los grupos establecidos y por otra, a las características transicionales de algunas unidades plutónicas. Estos hechos permiten suponer que las relaciones entre los «granitoides alcalinos y alumínicos de dos micas» y los «granitoides de tendencia calcoalcalina» no son tan independientes como se ha venido considerando en los modelos preexistentes. En función de la profundidad y etapa de emplazamiento y de las características petrológicas, las distintas unidades se han agrupado en las siguientes familias: - Granitoides sincinemáticos de emplazamiento relativamente profundo. - Granitoides sincinemáticos de emplazamiento somero. - Granitoides postcinemáticos de emplazamiento somero. Asimismo se detectan unidades plutónicas complejas, constituidas por varios granitos, a los cuales les corresponderían génesis diferentes, si se siguiesen los criterios previamente vigentes.[Abstract] This article summarizes part of the results of the project «Petrological, geochemical and geochronological caracterization and correlation of the granitic rocks of Galicia (provinces of A Coruña-Lugo)>>, executed on behalf of the Spanish Institute of Geology and Mining (1. G. M. E.). The Systematic investigation of the different granite plutons of the area evidences that the application of the criteria traditionally used for the classification of the granitic rocks in Galicia meets with serious difficulties. These are due to the rigidity of the established groups on the one hand and the transitional character of a number of plutonic units on the other hand. The study suggests that the relationship among the {<a1caline and aluminous two-mica granites» and the granitoids of the «ca1c-a1caline tendency is less independent than assumed in the hitherto used classification schemes and petrogenetical models. As a function of the depth and time of their emplacement and their petrological features, the different plutonic units are grouped into the following families: - Synkinematic, relatively deep-seated granitoid bodies. - Synkinematic, shallow-level granitoid bodies. - Postkinematic, shallow-level granitoid bodies. Attention is drawn to the occurrence of complex plutonic units whose constituent members would, according to the criteria of the pre-existing classification schemes, be petrogenetically unrelated or poorly related

Synthesis and solvatochromism studies of novel bis(indolyl)methanes bearing functionalized arylthiophene groups as new colored materials

The demand for dyes with solvatochromic properties has increased in the last few years, mainly due to their wide range of applications in the analytical and industrial fields, such as in the textile industry. The phenomenon of solvatochromism is associated with the differential solvation of the ground and excited states of the solvatochromic compounds, leading to an important tool for the study of the nature of solute–solvent interactions. In this paper we report the synthesis of new bis(indolyl)methane derivatives bearing arylthiophene spacers (2a–d) functionalized with electron-donating and electron- withdrawing groups, and the photophysical studies in different solvents, such as ethanol, acetonitrile, dichloromethane, trichloromethane, dimethylsulfoxide, diethylether and 1,4-dioxane. Aiming to explore their solvatochromic behavior in the ground and excited states, all solvents employed have different hydrogen-bond donor abilities. The largest colour modifications were visualized for compound 2b, the solution colours of which are orange in DMSO, blue in trichloromethane, green in dichloromethane and purple in 1,4-dioxane. A negative solvatochromism was observed in 2b and positive one in 2a, 2c and 2d.Fundação para a Ciência e a Tecnologia (FCT