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- Author or Editor: J. García x
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Abstract
Solid bisphenol-A epoxy resin of medium molecular mass was cured using a Lewis acid initiator (ytterbium(III) trifluoromethanesulfonate) in three different proportions (0.5, 1 and 2 phr). A kinetic study was performed in a differential scanning calorimeter. The complete kinetic triplet was determined (activation energy, pre-exponential factor, and integral function of the degree of conversion) for each system. A kinetic analysis was performed with an integral isoconversional procedure (free model), and the kinetic model was determined both with the Coats-Redfern method (the obtained isoconversional value being accepted as the effective activation energy) and through the compensation effect. All the systems followed the same isothermal curing model simulated from non-isothermal ones. The growth-of-nuclei Avrami kinetic model A3/2 has been proposed as the polymerization kinetic model. The addition of initiator accelerated the reaction especially when 2 phr was added. 0.5 and 1 phr showed very few kinetic differences between them.
Abstract
In this paper, novel results on the blue thermally stimulated luminescence (TSL) emission of ulexite (NaCaB5O6(OH)65H2O) have been studied. The four maxima appearing at 60, 110, 200 and 240C on the TSL glow curves of this borate could be respectively associated to: (i) the first dehydration (NaCaB5O6(OH)65H2O→NaCaB5O6(OH)63H2O), (ii) the creation-annihilation of the three-hydrated phase, (iii) the Na-coordinated chains dehydroxylation and the starting point of the alkali self-diffusion through the lattice and (iv) the amorphisation of the lattice. These results are fairly well correlated with the differential thermal analyses (DTA), in situ thermal observations under environmental scanning electron microscope (TESEM) and thermal X-ray diffraction (TXRD) techniques.
Abstract
The presence of226Ra and224Ra in suspended matter from an estuarine system which surrounds a phosphate fertilizer complex has been investigated. The results have confirmed an important radioactive impact from the industrial complex, since up to 2.5 Bq226Ra/g suspended matter (dry) has been measured. The influence of tides and seasonal conditions, through changes in salinity, has been found to be relevant. The distribution coefficients for226Ra between the suspended matter and the river water have been calculated. The values are in agreement by order of magnitude with those found in the literature, but they clearly depend on tidal state and seasonal conditions.
Mapping of quantitative trait loci (QTL) was carried out in a set of 114 RILs of the International Triticeae Mapping Initiative (ITMI) mapping population under salt stress. Seedling population was grown during 8 days, under salt treatment (Hoagland’s ½ strength + 110 mM NaCl, EC 12.4 mS/cm) and normal treatment (Hoagland’s ½ strength, EC 0.9 mS/cm). We calculated starch degradation, measuring the dry weight of the grains on the 4th, 6th and 8th days of culturing. Formation of biomass was calculated measuring leaf and root length on the 4th, 6th and 8th days of culture. Interval mapping resulted in 13 QTLs, 2 major QTLs (LOD> 3) and 11 minors QTLs (LOD> 2). A total of 10 QTLs were associated with saline treatment and 3 QTLs at normal treatment. The data show that a high percentage of QTLs were in chromosomes 2B (3, 23.0%), and 1A (3, 23.0%), followed by 4D (2, 13.6%).
Quantitative Trait Loci (QTL) mapping was carried out in a set of 114 lines of the International Triticeae Mapping Initiative (ITMI) mapping population for null nitrogen fertilization during two agricultural cycles. We quantified phenologic parameters (days to: ear emergency time, flowering time) and components of yield (number of plants and ears, plant height, leaf area, length and weight of ear, spikelet number, number and total weight of grains and by third in the ear, weight of thousand grains and total yield). Interval mapping resulted of 138 QTLs, of which 47 were catalogued as major QTLs (LOD ≥ 3.0) and 91 as minor QTLs (LOD 2.0 >0 2.9). The QTLs were distributed in 14 of the 21 chromosomes of wheat. The data showed that a high percentage of QTLs were in chromosomes 2D (49 or 35.5%), followed by 5A (22 or 15.9%), 1B (10 or 7.2%).
Abstract
Kinetics of thermosetting polymers curing is difficult to study by isothermal methods based on the differential scanning calorimetry (DSC) technique. The difficulty is due to the low sensitivity of the equipment for total reaction heat measurements during high temperature process. The aim of this paper is to display the equivalence between a dynamic model, the Ozawa method, and an isothermal isoconversional fit, which allows predicting the isothermal behavior of the resol resins cure through dynamic runs by DSC. In this work, lignin–phenol–formaldehyde and commercial phenol–formaldehyde resol resins were employed. In addition, the isothermal kinetic parameters for both resins were performed by means of transformation of the data obtained from the dynamic Ozawa method.
Abstract
Here we show a longitudinal analysis of the overall prestige of first quartile journals during the period between 1999 and 2009, on the subject areas of Scopus. This longitudinal study allows us to analyse developmental trends over times in different subject areas with distinct citation and publication patterns. To this aim, we first introduce an axiomatic index of the overall prestige of journals with ranking score above a given threshold. Here we demonstrate that, between 1999 and 2009, there was high and increasing overall prestige of first quartile journals in only four areas of Scopus. Also, there was high and decreasing overall prestige of first quartile journals in five areas. Two subject areas showed high and oscillating overall prestige of first quartile journals. And there was low and increasing overall prestige in four areas, since the 1999.
Abstract
Here we show a comparison of top economics departments in the US and EU based on a summary measure of the multidimensional prestige of influential papers in 2010. The multidimensional prestige takes into account that several indicators should be used for a distinct analysis of structural changes at the score distribution of paper prestige. We argue that the prestige of influential articles should not only consider one indicator as a single dimension, but in addition take into account further dimensions, since several different indicators have been developed to evaluate the impact of academic papers. After having identified the multidimensionally influential articles from an economics department, their prestige scores can be aggregated to produce a summary measure of the multidimensional prestige of research output of this department, which satisfies numerous properties.
Abstract
Calorific values and flammability changes during a year for forest waste originating from silviculture task in Galicia (NW Spain) are reported. These waste materials are becoming to be used as alternative fuels. The present study was made on several hardwood forest species. These forest species occupy nowadays approximately 30% of the total forest surface of Galicia. Calorific values were measured by static bomb calorimeter in an oxygen atmosphere. Flammability was determined using a standard epiradiator. Simultaneously, some other parameters such as elementary chemical composition, heavy metal contents, moisture, density, ash percentage after combustion in the bomb, and main bioclimatic characteristics, were also determined.
