Search

Your search keyword '"Manzano H."' showing total 149 results
Start Over Author "Manzano H."
149 results on '"Manzano H."'

1. Vinos de Altura del Noroeste Argentino – Características físico- químicas y Sensoriales

Author

Barroso R., Carbajal H., Ortiz H., Malaniuk M., Quenol H., Murgo M., Coria C., Videla R., Prieto S., Manzano H., Quini C., and Aruani C.

Subjects
Microbiology, QR1-502, Physiology, QP1-981, Zoology, QL1-991
Abstract

Se evaluaron 168 vinos experimentales, variedades Malbec, Cabernet Sauvignon, Syrah, y Tannat, de las cosechas 2014, 2015, y 2016, correspondientes a 24 viñedos de altura de las provincias de Salta y Jujuy, ubicados a altitudes desde 1575 hasta 2756 m.s.n.m. Los vinos fueron supeditados a análisis físico-químicos y sensoriales. Los datos físico químicos fueron analizados a través de ANOVA y Regresión Lineal Simple. Las similitudes y diferencias estadísticas de los datos sensoriales fueron evaluados mediante análisis de varianza (ANOVA), comparación múltiple de medias a través del test de Fisher (LSD), y análisis de componentes principales (PCA). Cada viñedo contó con un sensor de temperatura a través de los cuales se recopilaron datos a lo largo de todo el ciclo de la vid (años 2013 a 2015). Las temperaturas se utilizaron para la determinación de índices bioclimáticos de Winkler, Huglin e Índice de Noches Frescas. Los resultados indicarían una marcada influencia de las temperaturas y altitud en las variables del vino, principalmente las relacionadas al color y demás características sensoriales (P < 0.001,0.01 y 0.05), mostrando diferencias significativas entre los vinos de una misma variedad, provenientes de viñedos ubicados en distintas zonas vitícolas de características topográficas y de altitud diferentes.

Published
2019
Full Text
View/download PDF

2. C-A-S-H gels formed in alkali-activated slag cement pastes. Structure and effect on cement properties and durability

Author

Puertas F., Palacios M., Manzano H., Dolado J.S., Rico A., and Rodriguez J.

Subjects
Engineering (General). Civil engineering (General), TA1-2040
Abstract

The development of alternatives to traditional Portland cement produced with more eco-efficient processes (lower energy consumption and CO2 gas emissions) is an item on climate change and innovation agendas. Alkaline cements and concretes are an effective alternative to traditional cements. The structure of the C-S-H gel in Portland cements consists mostly of 14-nm tobermorite (with a chain length of five) and jennite (2-link chain). The mechanical properties of C-S-H gels can be explained in terms of the three types of packing found in these gels: low density (LD), high density (HD) and ultra-high density (UHD). The main reaction product in alkali-activated slag (AAS) cements is a C-A-S-H gel, which adopts different structures depending on the nature of the alkaline activator. When the activator is a NaOH solution (4 % Na2O by slag weight), the C-A-S-H gel formed has an intermediate structure between 14-nm tobermorite with a chain length of five links and 11-nm tobermorite with 14 links. When the activator is a waterglass solution (4 % Na2O by slag weight), traits characteristic of 14-nm tobermorite with 11-link chains and 11-nm tobermorite with a chain length of 14 co-exist in the structure of the C-A-S-H gel formed. This densely packed structure (with three HD states) yields excellent mechanical properties. Like the C-A-S-H gels obtained in NaOH (4% Na2O)-activated AAS paste, the C-A-S-H gels forming in AAS gels activated with waterglass have no UHD states. The structure and composition of these C-A-S-H gels determine strength development in AAS mortars and concretes as well as their resistance to aggressive chemicals.

Published
2014
Full Text
View/download PDF

3. Influence of BRAF and PIK3CA mutations on the efficacy of FOLFIRI plus bevacizumab or cetuximab as first-line therapy in patients with RAS wild-type metastatic colorectal carcinoma and

Author

Viéitez, J.M., Jiménez, P., Aguilar, E. Aranda, Gómez, A., Gil Calle, S., Salud, A., Valladares, M., Graña, B., García-Alfonso, P., Rivera, F., Quintero, G., Reina, J.J., González Flores, E., Salgado, M., Grande, E., Guillén, C., Garcia Carbonero, R., Flor, M.J., Safont, M.J., La Casta, A., Arévalo, S., Sastre, J., López López, R., Manzano, H., Guillot, M., Hernández Yagüe, X., Arrivi, A., Falcó, E., Gallego, J., Escudero, P., Cabezas, I., Juárez, A., Gálvez, E., Grávalos, C., Robles, L., Polo, E., Dueñas, R., Campos, J.M., Albert, A., Salinas, P., Montagut, C., Provencio, M., Ruiz Casado, A., Muñoz, J., Gil Raga, M., Chilet, M.R., González González, F.J., Massutí, B., López, A., Aparicio, J., Marín, M., Alfaro, J., Zanui, M., Gutiérrez Abad, D., García Tapiador, A.M., García-Girón, C., Molina Saera, J., Torres Sánchez, E., López, I., Bosch, C., Valero, J., Martínez de Prado, P., Cano, M.T., Reina-Zoilo, J.J., Salud-Salvia, A., Robles-Díaz, L., Gil, S., Asensio-Martínez, E., García-Paredes, B., López, R.L., Valladares-Ayerbes, M., Aranda, E., and Díaz-Rubio, E.

Published
2021
Full Text
View/download PDF

5. 383P An exosome-based liquid biopsy assay for predicting therapeutic outcomes in patients with metastatic colorectal cancer treated with anti-EGFR therapy: Results from prospective, first-line, PULSE and POSIBA trials

Author

Goel, A., primary, Xu, C., additional, Roy, S., additional, Esposito, F.M., additional, Helena, O., additional, Alonso, V., additional, Yubero Esteban, A., additional, Carlos, F-M., additional, Salud Salvia, M.A., additional, Gallego Plazas, J., additional, Rodriguez Monwbray, J.R., additional, Marta, M.M-R., additional, Fernandez, J., additional, Manzano, H., additional, Aparicio, J., additional, Feliu, J., additional, and Maurel, J., additional

Published
2022
Full Text
View/download PDF

6. Exploring mechanisms of hydration and carbonation of MgO and Mg(OH)₂ in reactive magnesium oxide-based cements

Author

Gardeh, M. G. (Mina Ghane), Kistanov, A. A. (Andrey A.), Nguyen, H. (Hoang), Manzano, H. (Hegoi), Cao, W. (Wei), Kinnunen, P. (Päivö), Gardeh, M. G. (Mina Ghane), Kistanov, A. A. (Andrey A.), Nguyen, H. (Hoang), Manzano, H. (Hegoi), Cao, W. (Wei), and Kinnunen, P. (Päivö)

Abstract

Reactive magnesium oxide (MgO)-based cement (RMC) can play a key role in carbon capture processes. However, knowledge on the driving forces that control the degree of carbonation and hydration and rate of reactions in this system remains limited. In this work, density functional theory-based simulations are used to investigate the physical nature of the reactions taking place during the fabrication of RMCs under ambient conditions. Parametric indicators such as adsorption energies, charge transfer, electron localization function, adsorption/dissociation energy barriers, and the mechanisms of interaction of H₂O and CO₂ molecules with MgO and brucite (Mg(OH)₂) clusters are considered. The following hydration and carbonation interactions relevant to RMCs are evaluated: (i) carbonation of MgO, (ii) hydration of MgO, carbonation of hydrated MgO, (iii) carbonation of Mg(OH)₂, (iv) hydration of Mg(OH)₂, and (v) hydration of carbonated Mg(OH)₂. A comparison of the energy barriers and reaction pathways of these mechanisms shows that the carbonation of MgO is hindered by the presence of H₂O molecules, while the carbonation of Mg(OH)₂ is hindered by the formation of initial carbonate and hydrate layers as well as presence of excessed H₂O molecules. To compare these finding to bulk mineral surfaces, the interactions of the CO₂ and H₂O molecules with the MgO(001) and Mg(OH)₂ (001) surfaces are studied. Therefore, this work presents deep insights into the physical nature of the reactions and the mechanisms involved in hydrated magnesium carbonates production that can be beneficial for its development.

Published
2022

11. Influence of BRAF and PIK3CA mutations on the efficacy of FOLFIRI plus bevacizumab or cetuximab as first-line therapy in patients with RAS wild-type metastatic colorectal carcinoma and <3 baseline circulating tumour cells: the randomised phase II VISNÚ-2 study

Author

Sastre, J., primary, García-Alfonso, P., additional, Viéitez, J.M., additional, Cano, M.T., additional, Rivera, F., additional, Reina-Zoilo, J.J., additional, Salud-Salvia, A., additional, Quintero, G., additional, Robles-Díaz, L., additional, Safont, M.J., additional, La Casta, A., additional, Gil, S., additional, Polo, E., additional, Asensio-Martínez, E., additional, García-Paredes, B., additional, López, R.L., additional, Guillot, M., additional, Valladares-Ayerbes, M., additional, Aranda, E., additional, Díaz-Rubio, E., additional, Jiménez, P., additional, Aguilar, E. Aranda, additional, Gómez, A., additional, Gil Calle, S., additional, Salud, A., additional, Valladares, M., additional, Graña, B., additional, Reina, J.J., additional, González Flores, E., additional, Salgado, M., additional, Grande, E., additional, Guillén, C., additional, Garcia Carbonero, R., additional, Flor, M.J., additional, Arévalo, S., additional, Sastre, J., additional, López López, R., additional, Manzano, H., additional, Hernández Yagüe, X., additional, Arrivi, A., additional, Falcó, E., additional, Gallego, J., additional, Escudero, P., additional, Cabezas, I., additional, Juárez, A., additional, Gálvez, E., additional, Grávalos, C., additional, Robles, L., additional, Dueñas, R., additional, Campos, J.M., additional, Albert, A., additional, Salinas, P., additional, Montagut, C., additional, Provencio, M., additional, Ruiz Casado, A., additional, Muñoz, J., additional, Gil Raga, M., additional, Chilet, M.R., additional, González González, F.J., additional, Massutí, B., additional, López, A., additional, Aparicio, J., additional, Marín, M., additional, Alfaro, J., additional, Zanui, M., additional, Gutiérrez Abad, D., additional, García Tapiador, A.M., additional, García-Girón, C., additional, Molina Saera, J., additional, Torres Sánchez, E., additional, López, I., additional, Bosch, C., additional, Valero, J., additional, and Martínez de Prado, P., additional

Published
2021
Full Text
View/download PDF

14. Metastatic Colorectal Cancer. First Line Therapy for Unresectable Disease

Author

Aparicio J, Esposito F, Serrano S, Falco E, Escudero P, Ruiz-Casado A, Manzano H, and Fernandez-Montes A

Subjects
targeted agents, colorectal cancer, chemotherapy, metastatic disease
Abstract

Colorectal cancer (CRC) is a commonly diagnosed malignancy. The prognosis of patients with unresectable, metastatic colorectal cancer (mCRC) is dismal and medical treatment is mainly palliative in nature. Although chemotherapy remains the backbone of treatment, the landscape is changing with the understanding of its heterogeneity and molecular biology. First-line therapy relies on a combination of chemotherapy and targeted therapies, according to clinical patient characteristics and tumor molecular profile. Here we review current evidence from randomized clinical trials for using chemotherapy doublets or triplets, and for the addition of bevacizumab or anti-epidermal growth factor receptor (EGFR) agents. Novel therapies developed for small, selected populations are also discussed.

Published
2020

15. 471P Identification and validation of a new prognostic score in metastatic colorectal cancer (mCRC): GEMCAD score

Author

Seguí, E., primary, Alonso-Orduna, V., additional, Sesma, A., additional, Martin-Richard, M., additional, Salud, A., additional, Fernández-Montes, A., additional, Fernández-Martos, C., additional, Ruiz-Casado, A., additional, Gallego, J., additional, Aparicio, J., additional, Gálvez, E., additional, Manzano, H., additional, Alcaide-Garcia, J., additional, Gallego, R., additional, Falco, E., additional, Esposito, F., additional, Oliveres, H., additional, Torres, F., additional, Feliu, J., additional, and Maurel, J., additional

Published
2020
Full Text
View/download PDF

16. Prospective Biomarker Study in Advanced RAS Wild-Type Colorectal Cancer: POSIBA Trial (GEMCAD 10-02)

Author

García-Albéniz X, Alonso V, Escudero P, Méndez M, Gallego J, Rodríguez JR, Salud A, Fernández-Plana J, Manzano H, Zanui M, Falcó E, Feliu J, Gil M, Fernández-Martos C, Bohn U, Alonso C, Calderero V, Rojo F, Cuatrecasas M, and Maurel J

Subjects
Clinical score, Cetuximab, neoplasms, Colorectal cancer, Biomarkers
Abstract

Background RAS testing is used to select patients with anti-epidermal growth factor receptor (EGFR) therapies sensitivity in metastatic colorectal cancer (mCRC). However, other biomarkers such as BRAF, PIK3CA/PTEN, and p-IGF-1R+/MMP7+ (double positive [DP] phenotype) have not been prospectively assessed to predict anti-EGFR resistance. Materials and Methods We designed a multicenter prospective trial (NCT01276379) to evaluate whether the biomarkers BRAF mutation, PIK3CA mutation/PTEN loss, and DP phenotype can improve the prediction for 12-months progression-free survival (PFS) over the use of clinical variables exclusively in patients with RAS wild-type (WT) mCRC treated with standard chemotherapy plus biweekly cetuximab as first-line therapy. The planned sample size was 170 RAS WT patients to detect a 20% difference in 12-month PFS based on the analysis of clinical and selected biomarkers (alpha = .05, beta = .2). The discriminatory capacity of the biomarkers was evaluated using receiver operating characteristic curves. Results We included 181 RAS WT patients. The biomarker distribution was as follows: BRAF mutant, 20 patients (11%); PIK3CA mutated/PTEN loss, 98 patients (58%); DP, 23 patients (12.7%). The clinical variables in the clinical score were progression status >0, left-sided tumor, and resectable liver metastasis as the only metastatic site. The area under the curve (AUC) of the score containing the clinical variables was 0.67 (95% confidence interval [CI], 0.60-0.75). The AUC of the score with clinical variables and BRAF mutational status was 0.68 (0.61-0.75, p = .37). The AUC of the score with clinical variables and PI3KCA mutation/PTEN status was 0.69 (0.61-0.76, p = .32). The AUC of the score with clinical variables and DP phenotype was 0.66 (0.58-0.73, p = .09). Conclusion The addition of BRAF, PIK3CA/PTEN, and DP to a clinical score does not improve the discrimination of 12-month PFS. Implications for Practice This prospective biomarker design study has important clinical implications because many prospective clinical trials are designed with the hypothesis that BRAF mutation per se and MEK and PIK3CA downstream pathways are critical for colorectal tumor survival. The results lead to the question of whether these pathways should be considered as passengers instead of drivers.

Published
2019

20. Kinetic Simulation of the Logarithmic Creep of Cement

Author

Massachusetts Institute of Technology. Department of Civil and Environmental Engineering, Massachusetts Institute of Technology. Department of Nuclear Science and Engineering, Masoero, Enrico, Ulm, Franz-Josef, Yip, Sidney, Pellenq, Roland Jm, Manzano, H., Del Gado, E., Massachusetts Institute of Technology. Department of Civil and Environmental Engineering, Massachusetts Institute of Technology. Department of Nuclear Science and Engineering, Masoero, Enrico, Ulm, Franz-Josef, Yip, Sidney, Pellenq, Roland Jm, Manzano, H., and Del Gado, E.

Abstract

Many amorphous materials display a logarithmic creep behavior, driven by the rare occurrence of complex, hardly detectable, microscopic, structural rearrangements. Following recent developments in experimental techniques and modeling, we develop here a new approach based on transition state theory and on activation energies computed from molecular simulations of shear tests. Our results predict the logarithmic creep of an amorphous, model structure of cement at the molecular and meso- scales. We investigate the interplay of cooperative processes at the different length-scales and establish connections with creep phenomena in other materials. © 2013 American Society of Civil Engineers.

Published
2018

21. Rational Design of Advanced Photosensitizers Based on Orthogonal BODIPY Dimers to Finely Modulate Singlet Oxygen Generation

Author

Epelde-Elezcano N., Palao E., Manzano H., Prieto-Castañeda A., Agarrabeitia A.R., Tabero A., Villanueva A., de la Moya S., López-Arbeloa Í., Martínez-Martínez V., Ortiz M.J. and Financial support from the MICINN (CTQ2013-48767-C3-3-R, MAT2014-51937-C3-2-P, MAT2014-51937-C3-3-P and MAT2015-68837-REDT) is gratefully acknowledged. The Basque Government (IT912-16) and Comunidad de Madrid (S2013/MIT-2850) are thanked for funding this research. A.T. thanks UAM for a predoctoral contract. V.M.M. acknowledges Ministerio de Econom?a y Competitividad MICINN for a ?Ram?n y Cajal? contract (RYC-2011-09505). N.E.E. acknowledges Universidad del Pa?s Vasco (UPV-EHU) and Universit? de Pau et Pays de l?Adour (UPPA) for a co-advised doctoral grant.

Published
2017

22. AcetylacetonateBODIPY-Biscyclometalated Iridium(III) Complexes: Effective Strategy towards Smarter Fluorescent Photosensitizer Agents

Author

Palao E., Sola-Llano R., Tabero A., Manzano H., Agarrabeitia A.R., Villanueva A., López-Arbeloa I., Martínez-Martínez V., Ortiz M.J. and Financial support from MINECO (MAT2014-51937-C-2-P and 3-P and MAT2015-68837-REDT), MICINN (CTQ2013-48767-C3-3-R), Comunidad de Madrid (S2013/MIT-2850) of Spain, and Gobierno Vasco (IT912-16) is gratefully acknowledged. V.M.M. thanks MINECO for a postdoctoral contract (RYC-2011-09505). R.S.L. thanks the UPV-EHU for a postdoctoral fellowship, and A.T. thanks the UAM for a predoctoral contract. The authors thank the technical and human support provided by SGIker of UPV/EHU and European funding (ERDF and ESF).

Published
2017

25. Rational Design of Advanced Photosensitizers Based on Orthogonal BODIPY Dimers to Finely Modulate Singlet Oxygen Generation

Author

Epelde-Elezcano N., Palao E., Manzano H., Prieto-Castañeda A., Agarrabeitia A.R., Tabero A., Villanueva A., de la Moya S., López-Arbeloa Í., Martínez-Martínez V., Ortiz M.J., Epelde-Elezcano N., Palao E., Manzano H., Prieto-Castañeda A., Agarrabeitia A.R., Tabero A., Villanueva A., de la Moya S., López-Arbeloa Í., Martínez-Martínez V., and Ortiz M.J.

Published
2017

26. Aluminum incorporation to dreierketten silicate chains

Author

Manzano, H., Dolado, J. S., and Ayuela, A.

Subjects
Aluminum silicates -- Research, Aluminum compounds -- Research, Chemical reactions -- Research, Chemicals, plastics and rubber industries
Published
2009

27. Prospective evaluation of BRAF, PI3K and PTEN as predictive and prognostic biomarkers in first-line advanced KRAS wild-type colorectal cancer treated with FOLFOX or FOLFIRI plus bi-weekly cetuximab. GEMCAD 10-02

Author

Alonso, V., primary, Emperador, P. Escudero, additional, Urena, M. Mendez, additional, Gallego, J., additional, Rodriguez, J.R., additional, Fernández, J., additional, Salud, A., additional, Falcó, E., additional, Manzano, H., additional, Zanui, M., additional, Gil, M., additional, Sarmiento, U. Bohn, additional, Martos, C. Fernández, additional, Calderero, V., additional, Ferrer, A.I., additional, Cuatrecasas, M., additional, Rojo, F., additional, Feliu, J., additional, Maurel, J., additional, and García-Albéniz, X., additional

Published
2016
Full Text
View/download PDF

29. PULSE, a phase 2 study of mFOLFOX6-panitumumab (P) with biomarker stratification as first-line chemotherapy (CT), in patients (pts) with KRAS (exon 2) metastatic colorectal cancer (mCRC). A GEMCAD 09-03 study

Author

Maurel, J., primary, Martos, C. Fernández, additional, Richard, M. Martín, additional, Alonso, V., additional, Méndez, C. Méndez, additional, Salud, A., additional, Pericay, C., additional, Aparicio, J., additional, Gallego, J., additional, Carmona, A., additional, Casado, E., additional, Manzano, H., additional, Horndler, C., additional, Rubini, M., additional, Cuatrecasas, M., additional, García-Albéniz, X., additional, and Feliu, J., additional

Published
2016
Full Text
View/download PDF

31. A model for the C-A-S-H gel formed in alkali-activated slag cements

Author

Puertas, Francisca, Palacios, Marta, Manzano, H., Sanchez Dolado, Jorge, and Rico, A.

Subjects
Microstructure-final, Cements, Atomistic modelling, Mechanical properties, Spectroscopy
Abstract

For first time, an experimental and computational study has been conducted to define a structural model for the C-A-S-H gel forming in alkali-activated slag (AAS) pastes that would account for the mechanical properties of these materials. The study involved a comparison with the C-S-H gel forming in a Portland cement paste. The structure of the C-A-S-H gels in AAS pastes depends on the nature of the alkali activator. When the activator is a NaOH, the structure of the C-S-H gel falls in between tobermorite 1.4 nm with a mean chain length of five, and tobermorite 1.1 nm with a mean length of 14. When waterglass is the activator the structure of the C-A-S-H gel is indicative of the co-existence of tobermorite 1.4 nm with a chain length of 11 and tobermorite 1.1 nm with a chain length of 14. This very densely packed structure gives rise to excellent mechanical properties.

Published
2011

36. 540P - Prospective evaluation of BRAF, PI3K and PTEN as predictive and prognostic biomarkers in first-line advanced KRAS wild-type colorectal cancer treated with FOLFOX or FOLFIRI plus bi-weekly cetuximab. GEMCAD 10-02

Author

Alonso, V., Emperador, P. Escudero, Urena, M. Mendez, Gallego, J., Rodriguez, J.R., Fernández, J., Salud, A., Falcó, E., Manzano, H., Zanui, M., Gil, M., Sarmiento, U. Bohn, Martos, C. Fernández, Calderero, V., Ferrer, A.I., Cuatrecasas, M., Rojo, F., Feliu, J., Maurel, J., and García-Albéniz, X.

Published
2016
Full Text
View/download PDF

37. 499P - PULSE, a phase 2 study of mFOLFOX6-panitumumab (P) with biomarker stratification as first-line chemotherapy (CT), in patients (pts) with KRAS (exon 2) metastatic colorectal cancer (mCRC). A GEMCAD 09-03 study

Author

Maurel, J., Martos, C. Fernández, Richard, M. Martín, Alonso, V., Méndez, C. Méndez, Salud, A., Pericay, C., Aparicio, J., Gallego, J., Carmona, A., Casado, E., Manzano, H., Horndler, C., Rubini, M., Cuatrecasas, M., García-Albéniz, X., and Feliu, J.

Published
2016
Full Text
View/download PDF

38. Modelos estructurales del empaquetamiento aleatorio de partículas esféricas de Tobermorita: una aproximación computacional sencilla

Author

Universidad de Sevilla. Departamento de Física de la Materia Condensada, González Teresa, R., Morales Flórez, Víctor, Manzano, H., Dolado, J. S., Universidad de Sevilla. Departamento de Física de la Materia Condensada, González Teresa, R., Morales Flórez, Víctor, Manzano, H., and Dolado, J. S.

Abstract

En este trabajo y con el objetivo de conjugar el punto de vista atomístico y coloidal, presentamos un método com- putacional Monte Carlo que reproduce el empaqueta- miento coloidal de nano-partículas esféricas cristalinas de tipo Tobermorita. Variando los parámetros computa- cionales de empaquetamiento diferentes estructuras tipo Low Density (LD) C-S-H y High Density (HD) C-S-H han sido creadas. Posteriormente, las estructuras resultantes de nuestros experimentos computacionales han sido analizadas en términos de sus densidades, áreas especí- ficas y propiedades mecánicas., In this work, and in order to bring together the atomistic and colloidal viewpoints, we will present a Monte Carlo computational scheme which reproduces the colloidal packing of nano-spherical crystalline tobermorite-like particles. Different Low Density (LD) C- S-H and High Density (HD) C-S-H structures will be developed just by varying the computational packing parameters. Finally, the structures resulting from our computational experiments will be analyzed in terms of their densities, surface areas and their mechanical properties.

Published
2010

42. Do Cement Nanotubes exist?

Author

Manzano, H., primary, Enyashin, A. N., additional, Dolado, J. S., additional, Ayuela, A., additional, Frenzel, J., additional, and Seifert, G., additional

Published
2012
Full Text
View/download PDF

50. Understanding and Controllingthe Reactivity of the Calcium Silicate phases from First Principles.

Author

Durgun, E., Manzano, H., Pellenq, R. J. M., and Grossman, Jeffrey C.

Subjects
*REACTIVITY (Chemistry), *CALCIUM silicates, *ELECTRONIC structure, *HYDRATION kinetics, *SUBSTITUTION reactions, *TEMPERATURE effect
Abstract

First principles calculations are employed to providea fundamental understanding of the relationship between the reactivityof synthetic calcium silicate phases and their electronic structure.Our aim is to shed light on the wide range of hydration kinetics observedin different phases of calcium silicate. For example, while the dicalciumsilicate (Ca2SiO4) phase slowly reacts withwater, the tricalcium silicate (Ca3SiO5) showsmuch faster hydration kinetics. We show that the high reactivity ofCa3SiO5is mainly related to the reactive sitesaround its more ionic oxygen atoms. Ca2SiO4doesnot contain these types of oxygen atoms, although experiments suggestthat impurities may play a role in changing the reactivity of thesematerials. We analyze the electronic structure of a wide range ofpossible substitutions in both Ca3SiO5and Ca2SiO4and show that while the influence of differenttypes of impurities on structural properties is similar, their effecton reactivity is very different. Our calculations suggest that thevariation of electronic structure is mainly related to the formationof new hybridized orbitals and the charge exchange between the impurityatoms and the bulk material. The charge localization upon introducingimpurities is quantified to predict candidate substitutions that couldincrease the reactivity of Ca2SiO4, which wouldbroaden the applicability of this lower temperature and thus lesscostly and energetically less demanding phase. [ABSTRACT FROM AUTHOR]

Published
2012
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results