La resistencia a los sulfatos de los cementos portland y su grado de finura de molido: análisis de su relación

This work has demonstrated the great influence that the specific surface of a Portland cement has on its qualification as a high or low resistance to sulfate ion attack - SIA, by means of the accelerated method ASTM C 452. For that purpose two Portland cements have been tested by means of that method. A Portland cement PY (3,83% C3A) (Type V(2)) with 3 different specific surfaces. The experimental results obtained have demonstrated that, according to the ASTM C452-68 method, a Portland Cement Type III(2) can be qualified as from Type V(2), and vice verse, according to its specific surface being adequated, or not, for each objective.Este trabajo ha demostrado la gran influencia que tiene la superficie específica de un cemento portland en su calificación como de alta o baja resistencia al ataque del ion sulfato mediante el método acelerado de ensayo ASTM C 452. Para este objetivo se han ensayado dos cementos portland mediante dicho método de ensayo. Un cemento portland PY (3,83% C3A), Tipo V (2) con 3 diferentes superficies específicas. Los resultados experimentales obtenidos han demostrado que, de acuerdo con el método ASTM C 452, un cemento portland tipo P III (2) puede ser calificado como de Tipo PY Tipo V (2)

A comprehensive study of a versatile magnetic refrigeration demonstrator

A versatile room temperature reciprocating magnetic refrigeration demonstrator has been designed, built and tested in order to evaluate the influence of different running parameters and to check suitable magnetocaloric materials for cooling at room temperature. A comprehensive study has been done with Gd spheres of 0.2-0.4 mm diameter arranged as a double regenerator with 15 g each. A Halbach Nd2e14B permanent magnet with a slot of 10 mm width has been used to generate the magnetic field with a maximum value of 1.4 T. The heat transfer fluid is a mixture of water and ethylene glycol in a 75-25 percentage. The demonstrator achieves a maximum no-load temperature span close to 20 K, with a regeneration ratio of ¿ = 4.1, and a maximum cooling power Qc=6 W at zero temperature span. COP values have been shown and different thermodynamic AMR cycles have been studied looking for the best parameters

The Cambrian of the Iberian Peninsula : an overview

This work is a brief overview of the Cambrian in the Iberian Peninsula, along with an updated review of lithostratigraphic and biostratigraphic data. A Cambrian correlation chart between the different stratigraphical units that have been established in the Iberian Peninsula is given. We also reappraise the Lower and Middle Cambrian regional stages in the light of new palaeontological data, and the different biozonations proposed with several palaeontological groups

Evidence for Quantization of Mechanical Rotation of Magnetic Nanoparticles

We report evidence of the quantization of the rotational motion of solid particles containing thousands of atoms. A system of CoFe 2 O 4 nanoparticles confined inside polymeric cavities has been studied. The particles have been characterized by the x-ray diffraction, transmission electron microscopy, plasma mass spectroscopy, ferromagnetic resonance (FMR), and magnetization measurements. Magnetic and FMR data confirm the presence of particles that are free to rotate inside the cavities. Equidistant, temperature-independent jumps in the dependence of the microwave absorption on the magnetic field have been detected. This observation is in accordance with the expectation that orbital motion splits the low-field absorption line into multiple lines

Tejada et al. Reply

A Reply to the Comment by Lin He

A Multidisciplinary Design Environment for Composite Rotor Blades

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97071/1/AIAA2012-1842.pd

An effective lowest Landau level treatment of demagnetization in superconducting mesoscopic disks

Demagnetization, which is inherently present in the magnetic response of small finite-size superconductors, can be accounted for by an effective $\kappa$ within a two-dimensional lowest Landau level approximation of the Ginzburg-Landau functional. We show this by comparing the equilibrium magnetization of superconducting mesoscopic disks obtained from the numerical solution of the three-dimensional Ginzburg-Landau equations with that obtained in the ``effective'' LLL approximation.Comment: 5 pages, 4 figures, submitted to Phys. Rev.

How extroversion affects student attitude toward the combined use of a wiki and video recording of group presentations

The aim of this paper is to analyze the effect of extroversion on students'' attitude toward the combined use of a wiki and the video recording of oral presentations to improve communication skills using a quantitative approach. The model includes stress because it is considered an important aspect in public speaking situations, especially so in a case like ours where the videos will be available to the class. The students’ enjoyment and the relative advantages of the learning activity are also included because they may have an influence on satisfaction and course recommendation. A survey was carried out among first-year undergraduate students. Using partial least squares methodology, the results suggest that extrovert individuals perceive less stress and more enjoyment when performing this activity, which results in them having a better attitude toward it. A total mediation effect of enjoyment between extroversion and attitude is found. Our findings also confirm that stress acts as a barrier to satisfaction, but it does not create a negative reaction toward the activity. Finally, the results show the mediation effect of attitude between the perceived relative advantages and satisfaction and between enjoyment and satisfaction

TEMPORAL AND SPATIAL DISTRIBUTION OF POACEAE POLLEN IN AREAS OF SOUTHERN UNITED KINGDOM, SPAIN AND PORTUGAL

Overall, longer Poaceae pollen seasons coincided with earlier pollen season start dates. Winter rainfall noticeably affects the intensity of Poaceae pollen seasons in Mediterranean areas, but this was not as important in Worcester. Weekly data from Worcester followed a similar pattern to that of Badajoz and Évora but at a distance of more than 1500 km and 4-5 weeks later

Application of simulations to thermodynamic properties of materials for magnetic refrigeration: A calorimetric approach to material’s magnetocaloric parameters

A magnetic refrigeration system is a complex system that involves the magnetocaloric effect (MCE) and the heat transfer problems working in a coupled manner. For this purpose, characterization of materials showing MCE is needed. Calorimetric characterization allows the obtention of thermodynamic variables needed for a precise quantification of this effect. More specifically, in systems with continuous magnetic field variation, in order to calculate the heat generation due to MCE, the knowledge of their magnetocaloric parameters—adiabatic temperature change (Formula presented.) and isothermal entropy change (Formula presented.)—and the heat capacity (Formula presented.), for every temperature and magnetic field present is needed. In this work, (Formula presented.) family materials have been either characterized or interpolated and used in numerical simulations in COMSOL Multiphysics™ software. The characterization was carried out with measurements of (Formula presented.), (Formula presented.) and (Formula presented.) and the calculation of other derived parameters, at different temperatures and magnetic fields