61 research outputs found
N1-Benzylidene-N2-(2-((2-((2-(benzylideneamino)ethyl)amino)ethyl)amino)ethyl)ethane-1,2-diamine
Synthesis of gold functionalised nanoparticles with the eranthis hyemalis lectin and preliminary toxicological studies on caenorhabditis elegans
The lectin found in the tubers of the Winter Aconite (Eranthis hyemalis) plant (EHL) is a Type II Ribosome Inactivating Protein (RIP). Type II RIPs have shown anti-cancer properties and have great potential as therapeutic agents. Similarly, colloidal gold nanoparticles are successfully used in biomedical applications as they can be functionalised with ligands with high affinity and specificity for target cells to create therapeutic and imaging agents. Here we present the synthesis and characterization of gold nanoparticles conjugated with EHL and the results of a set of initial assays to establish whether the biological effect of EHL is altered by the conjugation. Gold nanoparticles functionalised with EHL (AuNPs@EHL) were successfully synthesised by bioconjugation with citrate gold nanoparticles (AuNPs@Citrate). The conjugates were analysed by UV-Vis spectroscopy, Dynamic Light Scattering (DLS), Zeta Potential analysis, and Transmission Electron Microscopy (TEM).
Results indicate that an optimal functionalisation was achieved with the addition of 100 µL of EHL (concentration 1090 ± 40 µg/mL) over 5 mL of AuNPs (concentration [Au0] = 0.8 mM). Biological assays on the effect of AuNPs@EHL were undertaken on Caenorhabditis elegans, a free-living nematode commonly used for toxicological studies, that has previously been shown to be strongly affected by EHL. Citrate gold nanoparticles did not have any obvious effect on the nematodes. For first larval stage (L1) nematodes, AuNPs@EHL showed a lower biological effect than EHL. For L4 stage, pre-adult nematodes, both EHL alone and AuNPs@EHL delayed the onset of reproduction and reduced fecundity. These assays indicate that EHL can be conjugated to gold nanoparticles and retain elements of biocidal activity
Una aproximación estadística al estudio de la carbonatación del hormigón
Carbonation is one of the factors that conditions reinforced concrete durability, while porosity is one of the parameters that determines the carbonation rate: as a rule, the greater the porosity, the higher the rate. While many papers have been published on the effect of CO2 penetration in the pore solutions of concretes prepared under different experimental conditions, the literature has yet to address the joint effect of the factors considered in concrete design, such as the water/cement (w/c) ratio, type of cement, type of aggregate and presence of admixtures. The present paper discusses the findings of a statistical study of the impact of the aforementioned factors on both system porosity and carbonation rate. The type of cement, individually and in its interaction with the rest of the factors, proved to be the major determinant in concrete carbonation.La carbonatación es uno de los factores que supedita la durabilidad del hormigón armado, siendo la porosidad uno de los parámetros que más condicionan la velocidad de carbonatación. Son muchos los trabajos que estudian el efecto de la penetración del CO2 en la solución de los poros de hormigones preparados bajo distintas condiciones experimentales, sin embargo, no se encuentran referencias que analicen de forma conjunta el efecto de ciertos factores como son la relación agua/cemento (a/c ratio), el tipo de cemento, el tipo de árido y la presencia de aditivos, normalmente consideradas a la hora de diseñar un hormigón. En este trabajo se discuten los resultados obtenidos tras realizar un estudio estadístico del efecto que tienen los factores previamente mencionados, tanto en la porosidad de estos sistemas como en su nivel de carbonatación. El cemento tanto de manera individual como en sus interacciones con el resto de los factores es el factor que mas afecta a la carbonatación del hormigón
Influence of calcium aluminate cement (CAC) on alkaline activation of red clay brick waste (RCBW)
In this paper, the effect of calcium aluminate cement (CAC) additions on the alkali activation of red clay brick waste (RCBW) was studied at room temperature and at 65 C. RCBW was partially replaced with CAC (0e50 wt.%) and blends were activated with NaOH and sodium silicate solutions. The compressive strength evolution was tested on mortars and the nature of the reaction products was analysed by infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, microscopic studies and pH measurements. The results show that the use of CAC accelerates the activation process of RCBW so that 50 MPa were obtained in the blended mortars containing 40 wt.% CAC cured for 3 days at room temperature. CAC did not undergo normal hydration and only the C3AH6 phase was identified in the pastes blended with more than 30 wt.% CAC and cured at 65 C, while the main reaction product was a cementitious gel containing Ca and Al from CAC.The authors are grateful to the Spanish Ministry of Science and Innovation for supporting this study through Project GEOCEDEM BIA 2011-26947, and to FEDER funding.Reig Cerdá, L.; Soriano Martínez, L.; Borrachero Rosado, MV.; Monzó Balbuena, JM.; Paya Bernabeu, JJ. (2016). Influence of calcium aluminate cement (CAC) on alkaline activation of red clay brick waste (RCBW). Cement and Concrete Composites. 65:177-185. https://doi.org/10.1016/j.cemconcomp.2015.10.021S1771856
Influence of the activator concentration and calcium hydroxide addition on the properties of alkali-activated porcelain stoneware
Objective
The aim of this research was to investigate the influence of the alkali activator concentration and calcium dosage on the fresh behavior, compressive strength and microstructure of the binder produced by the alkali activation of porcelain stoneware waste, using NaOH and sodium silicate solution as activators.
Materials
Porcelain stoneware waste, NaOH and sodium silicate.
Method
Tested properties of mortars were the compressive strength and the setting times. Thermogravimetric analyses, microscopic studies, pH measurements, XRD and FTIR tests were used to assess the evolution of the microstructure developed.
Results
The results show that the activator concentration and calcium to sodium molar ratio strongly influence the fresh behavior and the hardening process of mortars. A linear evolution of compressive strength with sodium addition was observed when keeping the SiO2 concentration constant. Mortar samples with up to 36 MPa under compression were obtained after curing for 7 days at 65 °C.The authors are grateful to the Spanish Ministry of Science and Innovation for supporting this study through Project GEOCEDEM BIA 2011-26947, and to FEDER funding.Reig Cerdá, L.; Soriano Martínez, L.; Borrachero Rosado, MV.; Monzó Balbuena, JM.; Paya Bernabeu, JJ. (2014). Influence of the activator concentration and calcium hydroxide addition on the properties of alkali-activated porcelain stoneware. Construction and Building Materials. 63:214-222. https://doi.org/10.1016/j.conbuildmat.2014.04.023S2142226
Crustal Imbrication in an Alpine Intraplate Mountain Range: A Wide-Angle Cross-Section Across the Spanish-Portuguese Central System
Intraplate ranges are topographic features that can occur far from plate boundaries, the expected position of orogens as described in the plate tectonics theory. To understand the lithospheric structure of intraplate ranges, we focused on the Spanish-Portuguese Central System (SPCS), the most outstanding topographic feature in the central Iberian Peninsula. The SPCS is an Alpine range that exhumes Precambrian-Paleozoic rocks and is located at >200 km from the northern border of the Iberian microplate. Here, we provide a P-wave velocity model based on wide-angle seismic reflection/refraction data of the central SPCS (Gredos sector). Our results show: (a) a layered lithosphere characterized by three major interfaces: Conrad, Mohorovicic, and Hales discontinuities, (b) an asymmetry of the crust-mantle boundary under the SPCS, (c) the extent of the Variscan batholith forming the main outcrops of Gredos, and (d) the thinning of the lower crust toward the south. This model suggests that the exhumation of the SPCS basement was driven by a south-vergent thick-skinned thrust system, developed in the southern part of the SPCS and that promoted crustal imbrication and a Mohorovicic discontinuity's offset under the SPCS. Thus, the deformation mechanisms of the crust seem to be controlled by the presence of the late- to post-Variscan granitoids that assimilated the Variscan mid-crustal detachment creating a new rheological boundary. This tectonic structure allowed the formation of Alpine crustal-scale thrust systems that eased coupled deformation of the upper and lower crust, leading to limited underthrusting of both crustal layers.This study has been funded by the Ministry of Science, Innovation and Competitiveness through the Project CIMDEF (CGL2014-56548-P). IP is funded by the Spanish Government and the University of Salamanca (Beatriz Galindo grant BEGAL 18/00090). JA is funded by grant IJC2018-036074-I, funded by MCIN/AEI/10.13039/501100011033. DMP and FGL are also funded by grants CGL2015-71692 (MINECO/ FEDER) and PID2020-118822GB-I00 (MCIN/AEI/10.13039/501100011033).Peer reviewe
Alkali activation of vitreous calcium aluminosilicate derived from glass fiber waste
The properties and microstructure of alkali-activated (AA) vitreous calcium aluminosilicate (VCAS) are presented in this paper. VCAS is manufactured from a by-product of the glass fiber industry and has been activated using NaOH and KOH solutions. The microstructure and mechanical properties of AA VCAS pastes and mortars are reported. The results show that depending on the type and concentration of hydroxide solution used, mortar samples with compressive strengths up to 77 MPa can be formed after curing for three days at 65 °C. The research demonstrates the potential of VCAS to produce AA cements and the importance of alkali type and concentration in optimizing properties and microstructure.Mitsuuchi Tashima, M.; Soriano Martinez, L.; Borrachero Rosado, MV.; Monzó Balbuena, JM.; Cheeseman, CR.; Paya Bernabeu, JJ. (2012). Alkali activation of vitreous calcium aluminosilicate derived from glass fiber waste. 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Effect of curing time on the microstructure and mechanical strength development of alkali activated nbinders based on vitreous calcium aluminosilicate (VCAS). Bull. Mater. Sci. in press.Hemmings RT, Nelson RD, Graves PL, Cornelius BJ. White pozzolan composition and blended cements containing same. Patent US6776838. 2004.Provis, J. L., Lukey, G. C., & van Deventer, J. S. J. (2005). Do Geopolymers Actually Contain Nanocrystalline Zeolites? A Reexamination of Existing Results. Chemistry of Materials, 17(12), 3075-3085. doi:10.1021/cm050230iCriado, M., Fernández-Jiménez, A., de la Torre, A. G., Aranda, M. A. G., & Palomo, A. (2007). An XRD study of the effect of the SiO2/Na2O ratio on the alkali activation of fly ash. Cement and Concrete Research, 37(5), 671-679. doi:10.1016/j.cemconres.2007.01.013Rees, C. A., Provis, J. L., Lukey, G. C., & van Deventer, J. S. J. (2007). In Situ ATR-FTIR Study of the Early Stages of Fly Ash Geopolymer Gel Formation. 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Phase evolution of C-(N)-A-S-H/N-A-S-H gel blends investigated via alkali-activation of synthetic calcium aluminosilicate precursors
Stoichiometrically-controlled alkali-activated pastes containing calcium-(sodium) aluminosilicate hydrate (C-(N)-A-S-H) and sodium aluminosilicate hydrate (N-A-S-H) gels are produced by alkali-activation of high-purity synthetic calcium aluminosilicate powders. These powders are chemically comparable to the glass in granulated blast furnace slag, but without interference from minor constituents. The physiochemical characteristics of these gels depend on precursor chemical composition. Increased Ca content of the precursor promotes formation of low-Al, high-Ca C-(N)-A-S-H with lower mean chain length as determined by quantification of solid state nuclear magnetic resonance spectra, and less formation of calcium carboaluminate ‘Alumino-ferrite mono’ (AFm) phases. Increased Al content promotes Al inclusion and reduced crosslinking within C-(N)-A-S-H, increased formation of calcium carboaluminate AFm phases, and formation of an additional N-A-S-H gel. Small changes in precursor composition can induce significant changes in phase evolution, nanostructure and physical properties, providing a novel route to understand microstructural development in alkali-activated binders and address key related durability issues
Caracterización de la estructura cortical bajo la Zona Centro Ibérica: el experimento CIMDEF
X Congreso Geológico de España, 5-7 Julio 2021, Vitoria - GasteizEl Macizo Ibérico, en la parte occidental de la Península Ibérica, constituye una sección prácticamente completa del orogéno Varisco. Desde los años 90 este macizo ha sido objeto de diferentes estudios geofísicos para conocer la estructura a escala cortical. No obstante, en su parte central ¿ la Zona Centro Ibérica ¿ todavía no existían datos de sísmica profunda. Con el fin de aportar información geofísica en esta zona, en 2017 y 2019 se llevó a cabo el experimento de sísmica de reflexión y refracción de gran ángulo, CIMDEF (Central Iberian Mechanism of DEFormation). Este proyecto consiste en tres perfiles de orientación NNO-SSE y E-O de entre 130 y 330 km de longitud que atraviesan la cuenca del Duero, el Sistema Central y la cuenca del Tajo, lo que nos ha permitido construir un nuevo modelo de velocidades de ondas P en este sector de la Zona Centro Ibérica. Los resultados complementarán los modelos previos basados en interferometría sísmica de fases globales y sísmica de ruido ambiente (Andrés et al., 2019, 2020), aportando nuevos datos para validar la precisión de métodos sísmicos pasivos a escala litosférica en el orógeno Varisco.The Iberian Massif, in the western part of the Iberian Peninsula, constitutes a nearly complete section of the Variscan orogen. Since the 1990s it has been target of different geophysical studies to unravel the crustal structure. However, there was a remarkable lack of deep seismic sounding data in its central part – the Central Iberian Zone. To fill this gap, a wide-angle seismic reflection and refraction experiment, CIMDEF (Central Iberian Mechanism of DEFormation), was acquired in 2017 and 2019. CIMDEF consists of three NNW-SSE and E-W oriented profiles ranging between 130 and 330 km in length. These profiles run through the Duero basin, the Central System and the Tajo basin, allowing us to construct a new P-wave velocity model in this sector of the Central Iberian Zone. Furthermore, it will help to complement previous models in this area based on Global-Phase Seismic Interferometry and ambient seismic noise (Andrés et al., 2019, 2020), thus providing new constraints to validate the accuracy of passive seismic methods at lithospheric scale in the Variscan orogen.EU EIT-RawMaterials 17024_20170331_92304; MINECO: CGL2016-81964-REDE, CGL2014-56548-P)
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