Ab initio atomistic description of temperature-induced phase changes: The cases of zirconia and Ti-Y-co-doped zirconia

Zirconium dioxide, or zirconia, is a common and useful ceramic with a wide range of applications, from fuel cells to odontology. Its phase diagram is simple and well understood, having a structure which is monoclinic at temperatures up to 1500 K, tetragonal up to 2700 K and cubic up to 3000 K. Zirconia is rarely used in its pure form, being typically doped with Y2O3, MgO or TiO2, and in this regime its phase diagram becomes much more complex. In this context, ab initio molecular dynamics (AIMD) can provide a detailed atomistic description of the phase diagram of this system, accurately describing its stable phases and transition regions. In this work, 3 mol-% Y2O3 (3YSZ) crystals doped with different Ti contents were studied at the density-functional level. For Ti contents varying from 0 to 30 at%, a global search algorithm was first used to explore the 0 K potential-energy surface and determine the most stable sites for the added Ti atoms. It was found that, at low Ti compositions XTi, small TiO2 clusters form, followed by TiO2 channels and infinite TiO2 planes at larger XTi values, and that the highest stability is achieved at 9% Ti. AIMD simulations within the isothermal-isobaric NPT ensemble were then performed to characterize the temperature-dependent phase changes as a function of the Ti content, where it was found that the Ti-doped structures presented considerably smaller volume changes near the phase-change critical temperatures. These findings suggest that YSZ materials doped with a small amount of Ti are both energetically and kinetically more stable than the undoped counterparts, in the ideal proportion of 3% TiO2 for every 1% Y2O3 doping.Fil: Negreiros Ribeiro, Fábio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Ribeiro Ricci Lazar, Dolores. Comissao Nacional de Energia Nuclear. Centro de Lasers e Aplicacoes. Instituto de Pesquisas Energéticas e Nucleares; BrasilFil: Ussui, Valter. Comissao Nacional de Energia Nuclear. Centro de Lasers e Aplicacoes. Instituto de Pesquisas Energéticas e Nucleares; BrasilFil: De Lima, Nelson Batista. Comissao Nacional de Energia Nuclear. Centro de Lasers e Aplicacoes. Instituto de Pesquisas Energéticas e Nucleares; BrasilFil: Marchi, Juliana. Universidad Federal do Abc; BrasilFil: Dalpian, Gustavo Martini. Universidad Federal do Abc; Brasi

MANEJO DE PACIENTES HEMOFÍLICOS NA CLÍNICA ODONTOLÓGICA - UMA REVISÃO INTEGRATIVA DA LITERATURA

Abstract: Hemophilia is a genetic condition in which there are changes in the quantity and quality of plasma proteins that act in the blood clotting processes in a hereditary way. Objective: to carry out a scientific survey in the current literature on the management of hemophiliac patients in the dental clinic, highlighting aspects of the theme that answered the guiding question of the integrative review. Methodology: A literature search was carried out through the electronic database PubMed, using the search keywords, “MeSHterm”: “Hemophilia” AND “Dentistry”. The articles were evaluated according to the pre-established inclusion and exclusion criteria and the Boolean connector “AND” was used. Results and Discussion: Therefore, based on this search strategy, of the 20 articles that met the criteria, only 10 were selected to compose the study, as 10 articles did not address dental management in hemophiliac patients. Therefore, the dental management of hemophiliac patients is centered on hemostasis of the surgical field and on the administration of coagulation factors that are deficient according to the type of hemophilia. Final Considerations: Furthermore, as this is a disease that can involve systemic involvement, it is important to have a multidisciplinary approach, including dentists, hematologists and oral surgeons. Therefore, this integrative literature review included a detailed analysis of 10 articles, focusing on the dental management of hemophiliac patients. The results obtained successfully answered the research's guiding question.Resumen: La hemofilia es una condición genética en la que se producen cambios en la cantidad y calidad de las proteínas plasmáticas que actúan en los procesos de coagulación sanguínea de forma hereditaria. Objetivo: realizar un relevamiento científico en la literatura actual sobre el manejo de pacientes hemofílicos en la clínica dental, destacando aspectos de la temática que respondieron a la pregunta orientadora de la revisión integradora. Metodología: Se realizó una búsqueda bibliográfica a través de la base de datos electrónica PubMed, utilizando las palabras clave de búsqueda, “MeSHterm”: “Hemofilia” Y “Odontología”. Los artículos fueron evaluados según los criterios de inclusión y exclusión preestablecidos y se utilizó el conector booleano “Y”. Resultados y Discusión: Por lo tanto, con base en esta estrategia de búsqueda, de los 20 artículos que cumplieron con los criterios, solo 10 fueron seleccionados para componer el estudio, ya que 10 artículos no abordaron el manejo dental en pacientes hemofílicos. Por tanto, el manejo odontológico de los pacientes hemofílicos se centra en la hemostasia del campo quirúrgico y en la administración de factores de coagulación deficientes según el tipo de hemofilia. Consideraciones finales: Además, dado que se trata de una enfermedad que puede implicar afectación sistémica, es importante tener un abordaje multidisciplinario, incluyendo dentistas, hematólogos y cirujanos orales. Por lo tanto, esta revisión integradora de la literatura incluyó un análisis detallado de 10 artículos, enfocándose en el manejo dental de pacientes hemofílicos. Los resultados obtenidos respondieron con éxito a la pregunta orientadora de la investigación.Resumo: A hemofilia é uma condição genética em que ocorre alterações na quantidade e qualidade de proteínas plasmáticas que atuam nos processos de coagulação sanguínea de forma hereditária. Objetivo: fazer um levantamento científico na literatura atual sobre o manejo de pacientes hemofílicos na clínica odontológica, evidenciando aspectos da temática que respondessem à pergunta norteadora da revisão integrativa. Metodologia: Foi realizada uma busca da literatura através da base de dados eletrônicas PubMed, utilizando as palavras-chave para pesquisa, “MeSHterm”: “Hemophilia” AND “Dentistry”. Os artigos foram avaliados quanto aos critérios de inclusão e exclusão pré-estabelecidos e utilizou-se do conector booleano “AND’’. Resultados e Discussão: Portanto, a partir dessa estratégia de busca, dos 20 artigos que se adequaram aos critérios, apenas 10 foram selecionados para compor o estudo, já que 10 artigos não abordavam o manejo odontológico frente aos pacientes hemofílicos. Sendo assim, o manejo odontológico dos pacientes hemofílicos é centrado na hemostasia do campo cirúrgico e na administração de fatores de coagulação que se apresentam deficientes de acordo com o tipo de hemofilia. Considerações Finais: Ademais, por se tratar de uma doença que pode envolver comprometimento sistêmico, é importante que haja uma abordagem multidisciplinar incluindo dentistas, hematologistas e cirurgiões orais. Logo, a presente revisão integrativa de literatura contou com a análise detalhada de 10 artigos, com enfoque no manejo odontológico de pacientes hemofílicos. Os resultados obtidos responderam com êxito a pergunta norteadora da pesquisa

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Iron and oxygen vacancies at the hematite surface: Pristine case and with a chlorine adatom

Defect complexes play critical roles in the dynamics of water molecules in photoelectrochemical cell devices. For the specific case of hematite (α-Fe2O3), iron and oxygen vacancies are said to mediate the water splitting process through the localization of optically-derived charges. Using first-principles methods based on density-functional theory we show that both iron and oxygen vacancies can be observed at the surface. For an oxygen-rich environment, usually under wet conditions, the charged iron vacancies should be more frequent. As sea water would be an ideal electrolyte for this kind of device, we have also analyzed the effect of additional chlorine adsorption on this surface. While the chlorine adatom kills the charged oxygen vacancies, entering the void sites, it will not react with the iron vacancies, keeping them active during water splitting processes.Fil: Da Silva Alvim, Raphael. Universidade Federal Do Abc; BrasilFil: Negreiros Ribeiro, Fábio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Dalpian, Gustavo Martini. Universidade Federal Do Abc; Brasi

Reactivity and Catalysis by Nanoalloys

The chemical and catalytic properties of supported alloyed metal nanoparticles are reviewed. After describing the theoretical methods used to predict the electronic structure of nanoalloys and the experimental methods used to characterize their geometrical structure both ex-situ and in-situ and under operando conditions, we focus on the catalytic properties of these systems and the opportunities that alloying provides to modulate them. Prototypical processes of key industrial relevance are used as test examples: catalytic pollution control as three-way catalysts and NOx decomposition, the Fischer–Tropsch process, reforming of alkanes, electrocatalysis, and new energy resources as fuel cells and hydrogen storage. The aim of the chapter is to describe the interplay of experimental and theoretical characterization and technological heterogeneous catalytic systems for multi-element metal catalysts.Fil: Negreiros Ribeiro, Fábio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; Argentina. Consiglio Nazionale delle Ricerche; Italia. Istituto di Chimica dei Composti Organometallici; Italia. Istituto per i Processi Chimico Fisici; ItaliaFil: Sementa, Luca. Consiglio Nazionale delle Ricerche; Italia. Istituto di Chimica dei Composti Organometallici; Italia. Istituto per i Processi Chimico Fisici; ItaliaFil: Barcaro. Giovanni. Consiglio Nazionale delle Ricerche; Italia. Istituto di Chimica dei Composti Organometallici; Italia. Istituto per i Processi Chimico Fisici; ItaliaFil: Fechete, Ioana. Université de Technologie de Troyes; FranciaFil: Piccolo, Laurent. Centre National de la Recherche Scientifique; Francia. Université Claude Bernard Lyon 1; Francia. Institut de Recherches sur la Catalyse et l'Environnement de Lyon; FranciaFil: Fortunelli, Alessandro. Consiglio Nazionale delle Ricerche; Italia. Istituto di Chimica dei Composti Organometallici; Italia. Istituto per i Processi Chimico Fisici; Itali

Dynamical solvent effects on the charge and reactivity of Ceria-Supported Pt Nanoclusters

Supported Pt nanoparticles are key components in heterogeneous catalysis for energy and environment applications that involve vapor and wet conditions. In the latter case, the reaction proceeds at the catalyst-water interface where the solvent actively participates in the reaction mechanism. In this work, ab initio molecular dynamics simulations shed light on the effects of solvation on the reactivity and electronic properties of Pt6 nanocatalysts supported by ceria (CeO2), a highly reducible oxide. The calculated trajectories show that H2O molecules spontaneously dissociate at both the supported Pt6 cluster and at the ceria surface already at T = 350 K. Water dissociation leads to hydroxylation of the ceria surface and, most importantly, to the selective decoration of the metal-oxide periphery with hydroxide ions, which are stabilized by solvent-induced electronic effects and which quickly diffuse to the interfacial Pt sites via Grotthus-like proton chains. The periphery of the metal-oxide interface is thus identified as the active region of ceria-supported Pt clusters in wet environments. Solvation is shown to drive dynamic charge transfers across the metal/oxide interface that modify the cluster charge, a key parameter of the catalyst reactivity.Fil: Szabová, Lucie. Tsukuba University. National Institute For Materials Science; JapónFil: Camellone, Matteo Farnesi. Democritos Modeling Center For Research In Atomistic Simulation;Fil: Negreiros Ribeiro, Fábio. National Research Council-Istituto Officina dei Materiali. Democritos Modeling Center For Research In Atomistic Simulation; Italia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Matolín, Vladimír. Charles University. Faculty of Mathematics and Physics; República ChecaFil: Tateyama, Yoshitaka. Tsukuba University. National Institute For Materials Science; JapónFil: Fabris, Stefano. National Research Council-Istituto Officina dei Materiali. Democritos Modeling Center For Research In Atomistic Simulation; Itali