261 research outputs found
In-situ hydration studies of yeâelemite at early ages for understanding eco-cement performances'
PĂłster; ALBA User Meeting and VI AUSE Conferenc
Identification of Oocyst-Driven Toxoplasma gondii Infections in Humans and Animals through Stage-Specific SerologyâCurrent Status and Future Perspectives
The apicomplexan zoonotic parasite Toxoplasma gondii has three infective stages: sporozoites in sporulated oocysts, which are shed in unsporulated form into the environment by infected felids; tissue cysts containing bradyzoites, and fast replicating tachyzoites that are responsible for acute toxoplasmosis. The contribution of oocysts to infections in both humans and animals is understudied despite being highly relevant. Only a few diagnostic antigens have been described to be capable of discriminating which parasite stage has caused an infection. Here we provide an extensive overview of the antigens and serological assays used to detect oocyst-driven infections in humans and animals according to the literature. In addition, we critically discuss the possibility to exploit the increasing knowledge of the T. gondii genome and the various âomics datasets available, by applying predictive algorithms, for the identification of new oocyst-specific proteins for diagnostic purposes. Finally, we propose a workflow for how such antigens and assays based on them should be evaluated to ensure reproducible and robust results.Peer Reviewe
Rietveld quantitative phase analysis with molybdenum radiation
Building materials are very complex samples of worldwide importance; hence quantitative knowledge
of their mineralogical composition is necessary to predict performances. Rietveld quantitative phase
analysis (RQPA) allows a direct measurement of the crystalline phase contents of cements. We highlight
in this paper the use of laboratory X-ray powder diffraction (LXRPD) employing high-energy
radiation, molybdenum (Mo), for attaining the RQPA of cements. Firstly, we evaluate the accuracy
of RQPA employing a commercial calcium sulfoaluminate clinker with gypsum. In addition to
MoKα1 and MoKα1,2 radiations, Cu and synchrotron patterns are also analyzed for the sake of comparison.
Secondly, the assessment of the accuracy of RQPA results obtained using different radiations
(synchrotron, Mo, and Cu) and geometries (reflection and transmission) is performed by analyzing
two well-known commercial samples. As expected, for LXRPD data, accuracy in the RQPA results
improves as the irradiated volume increases. Finally, three very complex aged hydrated cements have
been analyzed using MoKα1-LXRPD and Synchrotron-XRPD. The main overall outcome of this
work is the benefit for RQPA of using strictly monochromatic MoKα1 radiation. Best laboratory results
arise from MoKα1 data as the effective tested volume is much increased but peak overlapping is
not swelledUniversidad de MĂĄlaga. Campus de Excelencia Internacional. AndalucĂa Tech
Quantitative phase Analisis: A comparative study of Mo and Cu strictly monochromatic radiations
A comparison of the Rietveld quantitative phase analyses (RQPA) obtained using Cu-Kα1, Mo-Kα1, and synchrotron strictly monochromatic radiations is presented. The main aim is to test a simple hypothesis: high energy Mo-radiation, combined with high resolution laboratory X-ray powder diffraction optics, could yield more accurate RQPA, for challenging samples, than well-established Cu-radiation procedure(s). In order to do so, three set of mixtures with increasing amounts of a given phase (spiking-method) were prepared and the corresponding RQPA results have been evaluated. Firstly, a series of crystalline inorganic phase mixtures with increasing amounts of an analyte was studied in order to determine if Mo-Kα1 methodology is as robust as the well-established Cu-Kα1 one. Secondly, a series of crystalline organic phase mixtures with increasing amounts of an organic compound was analyzed. This type of mixture can result in transparency problems in reflection and inhomogeneous loading in narrow capillaries for transmission studies. Finally, a third series with variable amorphous content was studied.
Limit of detection in Cu-patterns, ~0.2 wt%, are slightly lower than those derived from Mo-patterns, ~0.3 wt%, for similar recording times and limit of quantification for a well crystallized inorganic phase using laboratory powder diffraction was established ~0.10 wt%. However, the accuracy was comprised as relative errors were ~100%. Contents higher than 1.0 wt% yielded analyses with relative errors lower than 20%. From the obtained results it is inferred that RQPA from Mo-Kα1 radiation have slightly better accuracies than those obtained from Cu-Kα1. This behavior has been established with the calibration graphics obtained through the spiking method and also from Kullback-Leibler distance statistic studies. We explain this outcome, in spite of the lower diffraction power for Mo-radiation (compared to Cu-radiation), due to the larger volume tested with Mo, also because higher energy minimize pattern systematic errors and the microabsorption effect.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech
Clinkering and early age hydration characterization of Belite-Alite Calcium Sulfoaluminate (BACSA) cements
In this work, four BACSA clinkers with different compositions (belite ~ 70-55 wt %, alite ~ 10-15 wt % and yeâelimite ~ 10-15 wt %) were synthesized (at laboratory scale). Lime, gypsum, kaolin and sand were used as raw materials and clinkering temperatures from 1280 to 1300 ÂșC were studied. Every BACSA clinker was chemically and mineralogically characterized through X-ray fluorescence and laboratory X-ray powder diffraction (LXRPD), the latter in combination with the Rietveld methodology to obtain the full phase assemblage including amorphous contents. The clinker with the targeted composition (belite ~ wt 60 %, alite ~ 13 wt % and yeâelimite ~ 10 wt %) was chosen to perform the scaling-up (5 kg). To do so, the processing parameters (milling time and clinkering conditions) have been optimized.
Finally, the hydration of the corresponding BACSA cement pastes (prepared with the scaled-up clinker and gypsum) was studied through rheological measurements (at very early hydration time), calorimetry and impedance spectroscopy (first 24 h), and LXRPD in combination with the Rietveld methodology and G-factor method, at 1 and 7 hydration days to determine degree of hydration.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech
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 MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech
The use of mo and cu monochromatic radiations for quantitative phase analysis: study of the accuracy
Cement hydration is a very complex process in which crystalline phases are dissolving in water and after supersaturation hydrated crystalline and amorphous phases precipitate. Great efforts are being made to develop analytical tools to accurately quantify these processes and X-ray Powder Diffraction (XRPD) combined with Rietveld methodology is a suitable tool to quantify these complex mixtures and their time evolutions. However, some problems/drawbacks should be overcome to fully apply it to cement pastes characterization in order to get accurate phase analyses. In order to tackle this issue, a comparison of the Rietveld quantitative phase analyses (RQPA) obtained using Cu-Kα1, Mo-Kα1, and synchrotron strictly monochromatic radiations of three set of mixtures with increasing amounts of a given phase (spiking-method) is presented. The main aim is to test a simple hypothesis: high energy Mo-radiation, combined with high resolution laboratory X-ray powder diffraction optics, could yield more accurate RQPA, for challenging samples, than well-established Cu-radiation procedure(s). Firstly, a series of crystalline inorganic phase mixtures with increasing amounts of an analyte was studied in order to determine if Mo-Kα1 methodology is as robust as the well-established Cu-Kα1 one. Secondly, a series of crystalline organic phase mixtures with increasing amounts of an organic compound was analyzed. This type of mixture can result in transparency problems in reflection and inhomogeneous loading in narrow capillaries for transmission studies. Finally, a third series with variable amorphous content was studied. Limit of detection in Cu-patterns, ~0.2 wt%, are slightly lower than those derived from Mo-patterns, ~0.3 wt%, for similar recording times and limit of quantification for a well crystallized inorganic phase using laboratory powder diffraction was established ~0.10 wt%. From the obtained results it is inferred that RQPA from Mo-Kα1 radiation have slightly better accuracies than those obtained from Cu-Kα1.
The results obtained in the previous comparison have been taken into account to obtain accurate RQPA, including the amorphous component with internal standard methodology, of hydrating cement pastes. The final goal of this second study was understanding the early-stage hydration mechanisms of a variety of cementing systems (Ordinary Portland Cement or Belite Alite Yeâelimite cement) as a function of water content, superplasticizer additives and type and content of sulfate source. In order to do so, X-ray powder diffraction data were taken in-situ with the humidity chamber coupled to the Mo-Kα1 powder diffractometer. Some results of this ongoing investigation will be reported and discussed.Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech
Clinkering of calcium sulfoaluminate clinkers: polymorphism of ye'elimite
The manufacture of CSA cements is more environmentally friendly than that of OPC as it releases
less CO2. This reduction depends on CSA composition and is due to three factors: i) less emissions
from decarbonation in the kilns; ii) lower clinkering temperature, consequently less fuel is needed, and
iii) it is easier to grind, implying a depletion in indirect emissions.
CSA cements are prepared by mixing the clinker with different amounts of calcium sulfate as a set
regulator. Their main performances are fast setting time (followed by a rapid hardening), good chemical
resistance and, depending on the amount of the added sulfate source they can work as
shrinkage controllers.
CSA cements present a wide range of phase assemblages, but all of them contain over 50 wt% of
ye'elimite (C4A3s) jointly with belite (C2S), tetracalcium aluminoferrite (C4AF) and other minor
components such as CA, Cs, CsH2 and so on [1]. Ye'elimite is also included (~25 wt%) in BYF (Belite-
Ye'elimite-Ferrite) or BAY (Belite-Alite-Ye'elimite) clinkers.
Ye'elimite has a sodalite type structure with general composition, M4[T6O12]X. Stoichiometric ye'elimite
crystal structure at room temperature will be described in detailed. The role of different amounts of
minor elements on the synthetic procedure and crystal structures will be also presented [2,3].
This keynote will be also focused on a revision of the effect of raw materials on the mineralogical
composition of CSA, BYF and BAY. Specifically, the role of main elements contents in the ye'elimite
formation in these systems will be described. Moreover, the effect of minor elements on the
polymorphism of both ye'elimite and belite, especially on BYF and BAY clinkers, will be presented
[4,5,6].Universidad de MĂĄlaga. Campus de Excelencia Internacional AndalucĂa Tech. Spanish MINECO and FEDER [BIA2017-82391-R] research project and I3 [IEDI-2016-0079] program
Pressure release technique versus placebo applied to cervical and masticatory muscles in patients with chronic painful myofascial temporomandibular disorder: A randomised clinical trial
Background: The therapeutic approach to myofascial TMD should focus on pain relief and rehabilitation of function.
Objective: This study investigated whether pressure release technique (PRT) is effec- tive for reducing pain in people with chronic myofascial temporomandibular disorders (TMD).
Methods: A single-blinded randomised parallel-group trial, with 3 months follow-up was conducted. A total of 72 patients were randomly allocated to receive PRT or sham PRT. Primary outcome was pain assessed with a visual analogue scale (VAS). Secondary outcomes included pressure pain thresholds (PPTs), range of opening of the mouth (ROM), Neck Disability Index (NDI), Pain Catastrophizing Scale (PCS), Tampa Scale for Kinesiophobia (TSK-11), StateâTrait Anxiety Index (STAI) and Stateâ Trait Depression Index (ST-DEP). All parameters were assessed at baseline, at the end of the treatment and at 3 months follow-up. Statistical analysis was performed by ANOVA.
Results: There were significant main effects of time, group and interaction between time and group (F â„ 21.92; p < .001) on VAS pain. Post hoc tests showed a significant reduction in VAS pain scores in the PRT group (â„31.9%; p < .001). Effect sizes were moderate in the PRT group at all follow-up periods (â„1.25 Cohen's d). Also, there were significant effects of time in secondary outcomes (F â„ 9.65; p < .001), and there were also interactions between time and group (F â„ 3.82; p < .002) with better effects in the PRT group.
Conclusions: The inclusion of PRT to conventional management with occlusal splints and self-care management appears to be effective to improve self-reported levels of pain in patients with chronic myofascial TMD pain. Retrospectively registered (Clini calTrials.gov: NCT03619889).Depto. de EnfermerĂaDepto. de OdontologĂa Conservadora y PrĂłtesisFac. de EnfermerĂa, Fisioterapia y PodologĂaFac. de OdontologĂaTRUEpu
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