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1.
Phys Chem Chem Phys ; 23(11): 6600-6612, 2021 Mar 21.
Artículo en Inglés | MEDLINE | ID: mdl-33704311

RESUMEN

Size effects and structural modifications in amorphous TiO2 films deposited by atomic layer deposition (ALD) were investigated. As with the previously investigated ALD-deposited Al2O3 system we found that the film's structure and properties are strongly dependent on its thickness, but here, besides the significant change in the density of the films there is also a change in their chemical state. The thin near-surface layer contained a significantly larger amount of Ti+3 species and oxygen vacancies relative to the sample's bulk. We attribute this change in chemistry to the ALD specific deposition process wherein each different atomic species is deposited in turn, thereby forming a "corundum-like" structure of the near-surface layer resembling that found in the Al2O3 system. This, combined with the fact that each deposited layer starts out as a surface layer and maintains the surface structure over the next several following deposition cycles, is responsible for the overall decrease in the film density. This is the first time this effect has been shown in detail for TiO2, expending the previously discovered phenomenon to a new system and demonstrating that while similar effects occur, they can present in different ways for oxide systems with different structures and symmetries.

2.
Phys Chem Chem Phys ; 21(27): 14887-14891, 2019 Jul 10.
Artículo en Inglés | MEDLINE | ID: mdl-31233047

RESUMEN

The physical properties of nanocrystalline materials are known to be size dependent, owing to surface effects. Theoretically, a similar effect should also exist in amorphous materials. To examine this possibility, we carried out a study in which amorphous thin films of aluminum oxide were produced by atomic layer deposition (ALD) and studied by X-ray Absorption Near Edge Structure Spectroscopy (XANES) in grazing incidence geometry, as a function of the grazing angle. This allowed us to probe the Al local environment as a function of depth from the surface. The fraction of Al6 sites was found to be substantially lower at the surface than deeper in the film, meaning that the surface is relatively rich in Al4 sites. These results are in line with previous theoretical and experimental findings, shed further light on the structure and properties of amorphous nanometric materials and indeed indicate that size effects exist in amorphous nanometric materials.

3.
Science ; 358(6368): 1294-1298, 2017 12 08.
Artículo en Inglés | MEDLINE | ID: mdl-29217569

RESUMEN

In contrast to synthetic materials, materials produced by organisms are formed in ambient conditions and with a limited selection of elements. Nevertheless, living organisms reveal elegant strategies for achieving specific functions, ranging from skeletal support to mastication, from sensors and defensive tools to optical function. Using state-of-the-art characterization techniques, we present a biostrategy for strengthening and toughening the otherwise brittle calcite optical lenses found in the brittlestar Ophiocoma wendtii This intriguing process uses coherent nanoprecipitates to induce compressive stresses on the host matrix, functionally resembling the Guinier-Preston zones known in classical metallurgy. We believe that these calcitic nanoparticles, being rich in magnesium, segregate during or just after transformation from amorphous to crystalline phase, similarly to segregation behavior from a supersaturated quenched alloy.


Asunto(s)
Productos Biológicos/química , Carbonato de Calcio/química , Equinodermos/química , Nanopartículas/química , Animales , Cristalización , Magnesio/química , Estrés Mecánico
4.
Rev. argent. salud publica ; 3(12): 28-34, sept. 2012.
Artículo en Español | LILACS | ID: lil-698212

RESUMEN

INTRODUCCIÓN: El tema desarrollado en este escrito se basa en la indagación en la accesibilidad y derechos humanos en Salud Mental. La profundización en el conocimiento sobre la trayectoria de acceso a la atención de los padecimientos mentales desde diversos efectores generales puede contribuir a generar aportes innovadores que pueden ser orientadores en el diseño de políticas públicas. OBJETIVO: Analizar la trayectoria de accesibilidad en salud mental en los efectores generales de salud del subsector público, estudiando los casos de las provincias de Santa Fe y Tierra del Fuego (Argentina) en el marco de los dispositivos alternativos y/o sustitutivos del modelo asilar. MÉTODOS: Diseño cualitativo, de tipo descriptivo-analítico y de corte transversal, con una muestra no probabilística de carácter intencional. RESULTADOS: Con diferencias, las dos provincias analizadas se encuentran consolidando espacios alternativos y sustitutivos al manicomio. La presencia física del hospital monovalente (así esté situado dentro de la jurisdicción o fuera de su territorio) genera trayectorias que aún lo ubican como un efector más en el engranaje de la asistencia. El hospital general sigue generando resistencias para adecuar su dinámica institucional al abordaje de problemáticas vinculadas al padecimiento mental y a situaciones de vida complejas.CONCLUSIÓN: La atención primaria de la salud es un espacio privilegiado para fortalecer trayectorias de acceso con base en los derechos de los usuarios de los servicios de salud mental


INTRODUCTION: The main focus in this paper is related to the exploration of accessibility and human rights in mental health. Deepen the knowledge about access trajectory related to assist mental suffering of the different general services may contribute to generate innovative inputs to design public policies. OBJECTIVE: To analyze the accessibility in general health services of the public sector, considering the cases of the provinces of Santa Fe and Tierra del Fuego (Argentina), with in the context of schemes which are alternative and/or substitutive to asylum-centered model. METHODS: Qualitative descriptive, analytical and cross-sectional design, combined with an intentional and non-probabilistic sample. RESULTS: Although with differences, both provinces are consolidating alternative and substitutive services to the insane asylum. The physical presence of monovalent psychiatric hospital(whether located with in the jurisdiction or outside its territory) generates trajectories that still place it as a valid service in the health care scheme. The general hospital still generates resistance to adapt its institutional dynamics to dealing with issues related to mental suffering and complex life situations. CONCLUSIONS: Primary health care is a privileged space to strengthen access trajectories based on the rights of mental health services users


Asunto(s)
Humanos , Accesibilidad a los Servicios de Salud/organización & administración , Recolección de Datos , Derechos Humanos , Servicios Comunitarios de Salud Mental/organización & administración
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