Evaluation of electric properties of cement mortars containing pozzolans

[ES] En este trabajo se analiza la microestructura de morteros de cemento Portland, mediante medidas de impedancia eléctrica. Se comparan morteros de cemento sin y con dos sustituciones puzolánicas: residuo de catalizador de craqueo catalítico (FCC) y metacaolín (MK). Se describe el método de medida y se desarrolla el modelo de análisis de los espectros de impedancia eléctrica. Se definen tres parámetros eléctricos: resistividad eléctrica, exponente capacitivo y factor capacitivo. Se observa un aumento importante de la resistividad de los morteros con puzolana a partir de los 7 días de curado, sobre todo en morteros con MK. Este aumento está correlacionado con la fijación de cal de las puzolanas. Las propiedades capacitivas son diferentes a edad temprana, pero se igualan a los 148 días. Los resultados eléctricos y mineralógicos muestran que la evolución microestructural comienza antes en los morteros con MK que con FCC y que la microestructura final es diferente.[EN] In this paper the evolution of the microstructure of Portland cement mortar is analyzed, by using electrical impedance measurements. Cement mortars are compared without and with two pozzolanic substitutions: spent fluid catalytic cracking catalyst (FCC) and metakaolin (MK). The measurement method is described and the model for analyzing the electrical impedance spectra is developed. Three electrical parameters are defined: electrical resistivity, capacitance exponent, and capacitive factor. The results show a significant increase in resistivity of the mortars with pozzolans after 7 days of curing, especially in mortars with MK. This increase is correlated with lime-fixing by the pozzolans. The capacitive properties evolve differently at early age, but reach the same values after 148 days. The electrical and mineralogical data show that the evolution of the microstructure in the mortar with MK starts before it does in the mortars with FCC and that the final microstructure becomes different.Authors thank to Ministerio de Educacion (Spanish research plan) the financial support to the projects BIA 2006-15188-C03-02 y BIA 2004-00520, with FEDER co-financing. Also thank to Universidad Politecnica de Valencia (Vicerrectorado de Investigacion) the research grant for L.F. Lalinde (PPI-01-04 ref 5939) and financial support to the project PAID-05-09 ref 4302.Cruz González, JM.; Paya Bernabeu, JJ.; Lalinde Castrillón, LF.; Fita Fernández, IC. (2011). Evaluación de las propiedades eléctricas de morteros de cemento con puzolanas. Materiales de Construcción. 61(301):7-26. doi:10.3989/mc.2010.53709S7266130

Método específico para la evaluación medioambiental de los lagos de origen glaciar pirenaicos y su aplicación al lago de Sabocos

This study proposes a new method to asses the environmental state of the Pyrenean glacial lakes, based on the Water Framework Directive, the concept of ecological state and inspired by widely tested and used methodologies. Starting from a good ecological state as a reference term, a series of matrices are used to identify and characterize all anthropic impacts and pressures. Information regarding the most significant ones is then compared with the criteria of a panel of experts and finally the results are summarised in ICPA matrices of Impacts, Consequences, Proposals of Corrective Measures, and Applicability. This method has been tested in the glacial lake of Sabocos, finding that its ecological quality is lower than expected, based on the identification of some severe impacts. In order to subdue them, it has been proposed a plan of correcting measures and valued its applicability.En este trabajo se propone un nuevo método para la evaluación medioambiental de los lagos pirenaicos de origen glaciar a partir de la Directiva Marco del Agua, fundamentado en el concepto de estado ecológico e inspirado en metodologías ampliamente contrastadas. Partiendo de un estado ecológico de referencia se identifican y caracterizan todas las presiones e impactos antropogénicos mediante el empleo de una serie de matrices adaptadas. Los impactos más significativos son contrastados por un panel de expertos. Finalmente, los resultados se expresan mediante matrices ICPA de Impactos, Consecuencias, Propuestas de medidas correctoras y Aplicabilidad. Este método de evaluación medioambiental se ha aplicado al lago de Sabocos. Los resultados obtenidos muestran una calidad ecológica inferior a la esperada y que algunos de los impactos identificados son severos. Con el objetivo de mitigar tales afecciones, se han propuesto una serie de medidas correctoras y evaluado su aplicabilidad

BIOLOGICAL PROPERTIES AND CHEMICAL COMPOSITION OF JATROPHA NEOPAUCIFLORA PAX

Background: Ethnopharmacological relevance. Jatropha neopauciflora (Pax) is an endemic species of the Tehuacan- Cuicatlan Valley, Mexico. This species has long been used as a remedy to alleviate illnesses of bacterial, fungal and viral origin. Aim of the study. Experimentally test the traditional use of Jatropha neopauciflora in Mexican traditional medicine. Materials and methods. The methanol extract (MeOH1), of Jatropha neopauciflora (Euphorbiaceae) was obtained by maceration. Next, the methanol (MeOH2) and hexane (H) fractions were obtained. The essential oil was obtained by hydrodistillation. The extract, fractions and essential oil were analyzed by GC-MS. The antimicrobial activity was measured by the disc diffusion agar and radial inhibition growth methods. Results: The extract and fractions showed antibacterial activity against eleven strains (five Gram-positive and six Gramnegative) and a bacteriostatic effect in the survival curves for Staphylococcus aureus and Vibrio cholerae. The extract and fractions were also shown to have antifungal activity, particularly against Trichophyton mentagrophytes (CF50 = MeOH1: 1.07 mg/mL, MeOH2: 1.32 mg/mL and H: 1.08 mg/mL). The antioxidant activity of MeOH1 (68.6 g/mL) was higher than for MeOH2 (108.1 g/mL). The main compounds of the essential oil were -pinene, 1,3,8-p-menthatriene, ledene, mmenthane, linalyl acetate and 3-carene. The main compounds of MeOH1 were β-sitosterol, lupeol and pyrogallol; the main compounds of MeOH2 were β-sitosterol, spathulenol, coniferyl alcohol and lupeol; and the main compounds of H were β- sitostenone, -sitosterol and stigmasterol. Conclusions: This study indicates that Jatropha neopauciflora is a potential antibacterial and antifungal agent

K0S and Λ production in Pb-Pb collisions at sNN−−−−√=2.76 TeV

The ALICE measurement of K0S and Λ production at midrapidity in Pb-Pb collisions at sNN−−−√=2.76  TeV is presented. The transverse momentum (pT) spectra are shown for several collision centrality intervals and in the pT range from 0.4  GeV/c (0.6  GeV/c for Λ) to 12  GeV/c. The pT dependence of the Λ/K0S ratios exhibits maxima in the vicinity of 3  GeV/c, and the positions of the maxima shift towards higher pT with increasing collision centrality. The magnitude of these maxima increases by almost a factor of three between most peripheral and most central Pb-Pb collisions. This baryon excess at intermediate pT is not observed in pp interactions at s√=0.9  TeV and at s√=7  TeV. Qualitatively, the baryon enhancement in heavy-ion collisions is expected from radial flow. However, the measured pT spectra above 2  GeV/c progressively decouple from hydrodynamical-model calculations. For higher values of pT, models that incorporate the influence of the medium on the fragmentation and hadronization processes describe qualitatively the pT dependence of the Λ/K0S ratio

Measurement of D-s(+) product ion and nuclear modification factor in Pb-Pb collisions at root S-NN=2.76 TeV

Peer reviewe

phi-Meson production at forward rapidity in p-Pb collisions at root s(NN)=5.02 TeV and in pp collisions at root s=2.76 TeV

The first study of phi-meson production in p-Pb collisions at forward and backward rapidity, at a nucleonnucleon centre-of-mass energy root s(NN)= 5.02 TeV, has been performed with the ALICE apparatus at the LHC. The phi-mesons have been identified in the dimuon decay channel in the transverse momentum (p(T)) range 1 <p(T) <7GeV/c, both in the p-going (2.03 <y <3.53) and the Pb-going (-4.46 <y <-2.96) directions - where ystands for the rapidity in the nucleon-nucleon centre-of-mass - the integrated luminosity amounting to 5.01 +/- 0.19nb(-1) and 5.81 +/- 0.20nb(-1), respectively, for the two data samples. Differential cross sections as a function of transverse momentum and rapidity are presented. The forward-backward ratio for f-meson production is measured for 2.96Peer reviewe

Measurement of transverse energy at midrapidity in Pb-Pb collisions at root s(NN)=2.76 TeV

We report the transverse energy (ET) measured with ALICE at midrapidity in Pb-Pb collisions at root s(NN) = 2.76 TeV as a function of centrality. The transverse energy was measured using identified single-particle tracks. The measurement was cross checked using the electromagnetic calorimeters and the transverse momentum distributions of identified particles previously reported by ALICE. The results are compared to theoretical models as well as to results from other experiments. The mean ET per unit pseudorapidity (eta), , in 0%-5% central collisions is 1737 +/- 6(stat.) +/- 97(sys.) GeV. We find a similar centrality dependence of the shape of as a function of the number of participating nucleons to that seen at lower energies. The growth in at the LHC energies exceeds extrapolations of low-energy data. We observe a nearly linear scaling of with the number of quark participants. With the canonical assumption of a 1 fm/c formation time, we estimate that the energy density in 0%-5% central Pb-Pb collisions at root s(NN) = 2.76 TeV is 12.3 +/- 1.0 GeV/fm(3) and that the energy density at the most central 80 fm(2) of the collision is at least 21.5 +/- 1.7 GeV/fm(3). This is roughly 2.3 times that observed in 0%-5% central Au-Au collisions at root s(NN) = 200 GeV.Peer reviewe