3,559 research outputs found
In-situ early age hydration of cement-based materials by synchrotron X-ray powder diffraction
Cement based binders are building materials of worldwide importance. Since these samples are very complex, the knowledge/control of their mineralogical composition are essential to design and predict materials with specific/improved performance. Rietveld quantitative phase analysis (RQPA) allows the quantification of crystalline phases and, when combined with specific methodologies, as the addition of an internal standard or the external standard approach (G-factor), amorphous and non-crystalline phases can also be quantified. However, to carry out a proper RQPA in hydrated cementitious-materials, a good powder diffraction pattern is necessary. In this work, synchrotron X-ray powder diffraction (SXRPD) has been used, allowing in-situ measurements during the early-age hydration process.
This work deals with the early hydration study of cement-based materials. The studied samples were: a laboratory-prepared belite calcium sulphoaluminate (BCSAF) clinker (non-active) mixed with 10wt% gypsum, labelled G10B0; two active laboratory-prepared BCSAF clinkers (activated with 2wt% borax), one mixed with 10wt% gypsum and the other one with 10wt% monoclinic-bassanite, hereafter named G10B2 and B10B2, respectively; and an environmentally-friendly cement sample from Henkel, composed of bassanite mixed with 15wt% Portland cement and 10wt% Metakaolin, labelled H1.
Anhydrous G10B0 contains beta-belite and orthorhombic-ye'elimite as main phases, while alpha'H-belite and pseudo-cubic-ye'elimite are stabilized in G10B2 and B10B2, with the corresponding sulphate source. Anhydrous H1 contains monoclinic and hexagonal bassanite and alite as main phases.
Ye'elimite, in the non-active BCSAF cement pastes, dissolves at a higher pace than in the active one (degree of reaction is α~25% and α~10% at 1 h, respectively) (both prepared with gypsum), with the corresponding differences in ettringite crystallisation (degree of precipitation is α~30% and α~5%, respectively).
Moreover, the type of sulphate source has important consequences on the hydration of the active BCSAF cement pastes. Bassanite is quickly dissolved and it precipitates as gypsum within the first hour of hydration (in B10B2). At that time, ettringite starts to crystallize, and after 12 hours is almost fully crystallized, similar to G10B2.
In H1, bassanite transforms into gypsum within the first hour, being the principal hydration product; ettringite starts to be formed just after few hydration minutes.
These results are crucial in the understanding and development of improved cement materials.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Upgrade of the edge Charge Exchange Recombination Spectroscopy system at the High Field Side of ASDEX Upgrade
The upgrade of the high field side (HFS) edge charge exchange recombination spectroscopy (CXRS) system of ASDEX Upgrade is presented. This diagnostic provides temperature, rotation and radiance measurements of impurity species by taking advantage of the gas puff based CXRS technique (GP-CXRS). The system is formed by a fast piezoelectric valve, that injects thermal neutrals into the plasma, and two optical heads. The localized gas injection together with properly aligned lines of sights (LOS) lead to a high spatial resolution of 5–19 mm. Fast gas puff modulation allows a precise subtraction of the passive part of the signal. The existing poloidal optical head has been replaced with a new one to increase the radial resolution. The number of lines of sight (LOS) of the poloidal optical head has been increased from 8 to 16 covering around 7 cm of the plasma edge at the HFS. The same radial range is also viewed by a toroidal optical head. The neutral deposition, needed to calculate the impurity density profile, has been modelled using the FIDASIM code. A realistic gas puff geometry has been implemented in the code. The first measurements of impurity temperature, rotation and radiance utilizing the upgraded diagnostic are presented.Universidad de Sevilla PPITUS 2017EUROfusion Consortium 633053H2020 Marie-Skłodowska Curie programme (Grant No. 708257)Spanish Ministry of Economy and Competitiveness (Grant No. FJCI-201422139
Poloidal impurity asymmetry studies using the upgraded high field side edge CXRS diagnostic at ASDEX Upgrade
EUROfusion Consortium 63305
Characterization of edge poloidal impurity asymmetries at ASDEX Upgrade
EUROfusion Consortium 63305
In-out charge exchange measurements and 3D modelling of diagnostic thermal neutrals to study edge poloidal impurity asymmetries
A new method was developed to model the neutral population produced by the gas puff based charge exchange recombination spectroscopy systems at ASDEX Upgrade (AUG). With this method, the edge impurity density on the high field side (HFS) and low field side (LFS) can be obtained without the need to apply a neutral beam injection system. The neutral penetration needed for the calculation of the impurity density is obtained with a new gas puff module implemented in the FIDASIM code. The LFS impurity density profile evaluated with the new gas puff module matches the impurity density calculated with standard beam-based charge exchange diagnostics. Impurity temperature, rotation and density profiles at the HFS and LFS of an AUG H-mode discharge are presented. Edge impurity toroidal and poloidal flows show asymmetric structures. The impurity density asymmetries obtained with the new gas puff module are consistent with the observed flow structure
Dependencia funcional, deterioro cognitivo y características de la marcha en adultos mayores con enfermedades crónicas
Objetivo: Identificar el nivel y relación de dependencia funcional (DF), deterioro cognitivo (DC) y características de la marcha en adultos mayores (AM) con enfermedades crónicas, habitantes del área metropolitana de Saltillo, Coahuila.
Método: Diseño descriptivo correlacional. Muestra constituida por 105 AM de 60 años o más, usuarios de los Centros de Atención e Integración Familiar (CAIF). El tamaño de la muestra se determinó a través del paquete estadístico nQuery Advisor 7.0 considerando análisis de correlación bivariada, nivel de significancia de 0.5 y potencia del 95%. El muestreo fue por conveniencia. La recolección de datos se realizó a través de una cédula de datos socio-demográficas conjuntamente con cuatro instrumentos: para DF 1. Actividades Básicas de la Vida Diaria (AVD) y 2. Actividades Instrumentales de la Vida Diaria (AIVD); para DC 3. Mini Mental State Examination MMS-E; para las características de la marcha, 4. Sistema para Análisis de Marcha GaitRite ©, alphas de 0.730, 0.765, 0.720 y 0.811, respectivamente.
Resultados. La edad promedio de los AM participantes es de 75 años (X = 75 ± 6) y escolaridad de 5 años (X = 5 ± 3). La mayor parte son mujeres (81.9%); que viven sin pareja (74.3%) y reportan alguna enfermedad crónico-degenerativa (65%) como Diabetes, 32.4%; Hipertensión, 61% y Enfermedades Articulares, 42%. La prevalencia de: dependencia severa en ABVD 5.7% y AIVD 21.9 %; DC 24 %; Los AM con mayor edad y menor escolaridad, reportan mayor grado de DC (r= .251; p<.05; r= -.259; p<.05, respectivamente) y dependencia para realizar ABVD (r=.297; p<.05) y AIVD (r=.351; p<.05); Por lo menos, el 30% de AM presentabó dificultades para mantener el equilibrio. Además, el 60% presentó dificultades para sentarse porque tienen problemas al medir la distancia entre su propio cuerpo y la silla, caen en la silla o se apoye en él con movimientos inseguros. 29% presentaba dificultades para elevar su pie derecho completamente.
Discusión y Conclusiones. Los resultados de este estudio confirman lo que la literatura reporta acerca de la prevalencia y asociación de DF, DC y presencia de enfermedades crónicas características del AM como Diabetes e Hipertensión. Es necesario profundizar en el análisis de este estudio incorporando mediciones acerca del tiempo de diagnóstico de la enfermedad crónica, co-morbilidad, síntomas de depresión y diferencias de género, entre otros aspectos. También los factores asociados a la problemática de la marcha. Para el profesional de Enfermería, la continuidad de este fenómeno de estudio, fortalecerá el cuerpo de conocimientos disciplinares y la atención a las complejas necesidades de cuidado a la salud que demanda este segmento de la población. Palabras Clave: Adulto Mayor, Dependencia Funcional, Deterioro Cognitivo, Marcha
VAMOS: a Pathfinder for the HAWC Gamma-Ray Observatory
VAMOS was a prototype detector built in 2011 at an altitude of 4100m a.s.l.
in the state of Puebla, Mexico. The aim of VAMOS was to finalize the design,
construction techniques and data acquisition system of the HAWC observatory.
HAWC is an air-shower array currently under construction at the same site of
VAMOS with the purpose to study the TeV sky. The VAMOS setup included six water
Cherenkov detectors and two different data acquisition systems. It was in
operation between October 2011 and May 2012 with an average live time of 30%.
Besides the scientific verification purposes, the eight months of data were
used to obtain the results presented in this paper: the detector response to
the Forbush decrease of March 2012, and the analysis of possible emission, at
energies above 30 GeV, for long gamma-ray bursts GRB111016B and GRB120328B.Comment: Accepted for pubblication in Astroparticle Physics Journal (20 pages,
10 figures). Corresponding authors: A.Marinelli and D.Zaboro
f(R) theories
Over the past decade, f(R) theories have been extensively studied as one of
the simplest modifications to General Relativity. In this article we review
various applications of f(R) theories to cosmology and gravity - such as
inflation, dark energy, local gravity constraints, cosmological perturbations,
and spherically symmetric solutions in weak and strong gravitational
backgrounds. We present a number of ways to distinguish those theories from
General Relativity observationally and experimentally. We also discuss the
extension to other modified gravity theories such as Brans-Dicke theory and
Gauss-Bonnet gravity, and address models that can satisfy both cosmological and
local gravity constraints.Comment: 156 pages, 14 figures, Invited review article in Living Reviews in
Relativity, Published version, Comments are welcom
Limits on anomalous trilinear gauge boson couplings from WW, WZ and Wgamma production in pp-bar collisions at sqrt{s}=1.96 TeV
We present final searches of the anomalous gammaWW and ZWW trilinear gauge
boson couplings from WW and WZ production using lepton plus dijet final states
and a combination with results from Wgamma, WW, and WZ production with leptonic
final states. The analyzed data correspond to up to 8.6/fb of integrated
luminosity collected by the D0 detector in pp-bar collisions at sqrt{s}=1.96
TeV. We set the most stringent limits at a hadron collider to date assuming two
different relations between the anomalous coupling parameters
Delta\kappa_\gamma, lambda, and Delta g_1^Z for a cutoff energy scale Lambda=2
TeV. The combined 68% C.L. limits are -0.057<Delta\kappa_\gamma<0.154,
-0.015<lambda<0.028, and -0.008<Delta g_1^Z<0.054 for the LEP parameterization,
and -0.007<Delta\kappa<0.081 and -0.017<lambda<0.028 for the equal couplings
parameterization. We also present the most stringent limits of the W boson
magnetic dipole and electric quadrupole moments.Comment: 10 pages, 5 figures, submitted to PL
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