29Si Hyperfine Structure of the E'_\alpha Center in Amorphous Silicon Dioxide

We report a study by electron paramagnetic resonance (EPR) on the E'_\alpha point defect in amorphous silicon dioxide (a-SiO2). Our experiments were performed on gamma-ray irradiated oxygen-deficient materials and pointed out that the 29Si hyperfine structure of the E'_alpha consists in a pair of lines split by 49 mT. On the basis of the experimental results a microscopic model is proposed for the E'_alpha center, consisting in a hole trapped in an oxygen vacancy with the unpaired electron sp3 orbital pointing away from the vacancy in a back-projected configuration and interacting with an extra oxygen atom of the a-SiO2 matrix.Comment: 4 page

Relación de la ganancia solar, la aislación términa y los costos de calefacción solar/auxiliar en función de la forma edilicia.

A través de la arquitectura sustentable se  busca construir edificios cuyo impacto sobre el medio ambiente sea mínimo o nulo de manera de no comprometer los recursos para el futuro

Prácticas y técnicas materiales en la producción arquitectónica eco-ambiental

Este trabajo aborda las transformaciones tecnológicas en la producción arquitectónica respecto a las condicionantes eco-ambientales. Desde este horizonte, los proyectos de arquitectura enfrentan problemas de optimización, racionalidad y eficiencia energética, así como el control climático y la adecuada inserción en el contexto medio-ambiental. Esto significa una alternativa para ensayar prácticas y técnicas materiales con respecto a la estabilización termodinámica. 

Functional Living Skills: A Non-Immersive Virtual Reality Training for Individuals with Major Neurocognitive Disorders

The loss of functional living skills (FLS) is an essential feature of major neurocognitive disorders (M-NCD); virtual reality training (VRT) offers many possibilities for improving FLS in people with M-NCD. The aim of our study was to verify the effectiveness of a non-immersive VRT on FLS for patients with M-NCD. VRT was carried out for 10 to 20 sessions, by means of four 3D apps developed in our institute and installed on a large touch screen. The experimental group (EG) and the control group (CG) included 24 and 18 patients with M-NCD, respectively. They were administered the in vivo test (in specific hospital places reproducing the natural environments) at T1 (pre-training) and T3 (post-training); at T2, only EG was administered VRT. Statistically significant differences between EG and CG in all the in vivo tests were found in the number of correct responses; during VRT, the number of correct responses increased, while the execution times and the number of clues decreased. The improvement in the in vivo tests appeared to be related to the specific VRT applied. The satisfaction of participants with the VRT was moderate to high

Tecnología constructiva y cultura ambiental Edificio Enrico Tedeschi caso de estudio sobre construcción sustentable

CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia SolarRESUMEN: El trabajo expone cómo los criterios formales de la instancia constructiva material son determinante para la ecuación arquitectura / sustentabilidad. El Edificio FAUD / Enrico Tedeschi de 1960, es fuente de referencia para la investigación. Se destacan criterios materiales y formales respecto de la tecnología y la materialización para el desarrollo progresivo de un tipo arquitectónico referente para un cambio en la cultura material generacional. La estricta racionalidad constructiva y la lógica de la tecnicidad, son las principales razones para proporcionar una guía de validación relativa a los procedimientos constructivos sustentables. Basado en la metodología del redibujo y de monitoreo ambiental, se presenta una controversia entre la capacidad tectónica estructural y la racionalidad ambiental. La falta de aislamiento y estanqueidad del cerramiento requiere que los parámetros térmico interior estén supeditados al acondicionamiento mecánico adicional. Se simula la posibilidad de una adecuación de eficiencia energética siguiendo los patrones propios de la materialización en diálogo entre la compatibilidad tectónica y la racionalidad ambiental.ABSTRACT: The work exposes how the formal criteria of the material constructive instance are decisive for the architecture / sustainability equation. The FAUD / Enrico Tedeschi Building from 1960 is a reference source for research. Material and formal criteria are highlighted regarding technology and materialization for the progressive development of an architectural type of reference for a change in generational material culture. Constructive rationality and the logic of technicality are the main reasons for providing a validation guide regarding sustainable construction procedures. Based on the redrawing and environmental monitoring methodology, there is a controversy between structural tectonic capacity and environmental rationality. Little insulation and airtightness of the enclosure requires that the interior thermal parameters be subject to additional mechanical conditioning. The possibility of an energy efficiency adaptation is simulated following the patterns of the materialization in dialogue between tectonic compatibility and environmental rationality.info:eu-repo/semantics/publishedVersio

Delocalized Nature of the E'-delta Center in Amorphous Silicon Dioxide

We report an experimetal study by Electron Paramagnetic Resonance (EPR) of E'-delta point defect induced by gamma ray irradiation in amorphous SiO2. We obtained an estimetion of the intensity of the 10 mT doublet characterizing the EPR spectrum of such a defect arising from hyperfine interaction of the unpaired electron with a 29Si (I=1/2) nucleus. Moreover, determining the intensity ratio between this hyperfine doublet and the main resonance line of E'-delta center, we pointed out that unpaired electron wave function of this center is actually delocalized over four nearly equivalent silicon atoms.Comment: approved for publication in Physical Review Letter

Characterization of E'delta and triplet point defects in oxygen deficient amorphous silicon dioxide

We report an experimental study by electron paramagnetic resonance (EPR) of gamma ray irradiation induced point defects in oxygen deficient amorphous SiO2 materials. We have found that three intrinsic (E'gamma, E'delta and triplet) and one extrinsic ([AlO4]0) paramagnetic centers are induced. All the paramagnetic defects but E'gamma center are found to reach a concentration limit value for doses above 10^3 kGy, suggesting a generation process from precursors. Isochronal thermal treatments of a sample irradiated at 10^3 kGy have shown that for T>500 K the concentrations of E'gamma and E'delta centers increase concomitantly to the decrease of [AlO4]0. This occurrence speaks for an hole transfer process from [AlO4]0 centers to diamagnetic precursors of E' centers proving the positive charge state of the thermally induced E'gamma and E'delta centers and giving insight on the origin of E'gamma from an oxygen vacancy. A comparative study of the E'delta center and of the 10 mT doublet EPR signals on three distinct materials subjected to isochronal and isothermal treatments, has shown a quite general linear correlation between these two EPR signals. This result confirms the attribution of the 10 mT doublet to the hyperfine structure of the E'delta center, originating from the interaction of the unpaired electron with a nucleus of 29Si (I=1/2). Analogies between the microwave saturation properties of E'gamma and E'delta centers and between those of their hyperfine structures are found and suggest that the unpaired electron wave function involves similar Si sp3 hybrid orbitals; specifically, for the E'delta the unpaired electron is supposed to be delocalized over four such orbitals of four equivalent Si atoms.Comment: Approved for publication in Physical Review

Idiopathic eosinophilic parotitis in an eight-year-old boy: a case report

<p>Abstract</p> <p>Introduction</p> <p>A number of medical conditions, some of them recently reported, are associated with an increased production of eosinophils. We report the first case of eosinophilic parotitis in the literature.</p> <p>Case presentation</p> <p>The patient was an eight-year-old Caucasian boy who presented with a two-year history of recurring acute parotitis with no fever. He had had a total of five episodes with no response to antibiotics, but remission had been achieved with oral corticosteroid therapy. We performed allergy tests for inhalant and food allergens and for haptens, but the results were all negative. The results of echography ruled out sialodochitis. Instead, a swab from the parotid duct led to the detection of a high number of eosinophils.</p> <p>Conclusions</p> <p>This report is first in the literature to describe a case of eosinophilic parotitis, and we suggest that a cytological assessment, which is quite simple yet rarely used by physicians, be performed when patients with parotitis of uncertain origin are under evaluation.</p

Origin of the solid-state luminescence of MIL-53(Al) and its connection to the local crystalline structure

Metal-organic frameworks (MOFs) are extensively studied due to their unique surface properties, enabling many intriguing applications. Breathing MOFs, a subclass of MOFs, have gained recent interest for their ability to undergo structural changes based on factors like temperature, pressure, adsorbed molecules. Certain MOFs also exhibit remarkable optical properties useful for applications such as sensors, light-emitting diodes, and scintillators. The most promising MOFs possess high porosity, breathing properties, and photoluminescence activities, allowing for improved device responsiveness and selectivity. Understanding the relationship between crystal structures and photoluminescence properties is crucial in these cases. As studies on this topic are still very limited, we report for the first time an exhaustive study on the solid-state luminescence of the breathing MOF MIL-53(Al), that can stabilize in three different crystalline structures: open-pore, hydrated narrow-pore and closed-pore. We unveil a fascinating solid-state luminescence spectrum, comprising three partially overlapping bands, and elucidate the intricate electronic transitions within each band as well as their intimate correlation with the local crystalline structures. Our characterizations of spectroscopic properties and decay times provide a deeper understanding of the luminescent behaviour of MIL-53(Al) and demonstrate that is possible to identify present crystalline structures by optical measurements or to modify the optical properties inducing structural transitions for this type of materials. These insights could help to design next-generation, selective sensors or smart light emitting devices

Ultrafast Interface Charge Separation in Carbon Nanodot-Nanotube Hybrids

Carbon dots are an emerging family of zero-dimensional nanocarbons behaving as tunable light harvesters and photoactivated charge donors. Coupling them to carbon nanotubes, which are well-known electron acceptors with excellent charge transport capabilities, is very promising for several applications. Here, we first devised a route to achieve the stable electrostatic binding of carbon dots to multi- or single-walled carbon nanotubes, as confirmed by several experimental observations. The photoluminescence of carbon dots is strongly quenched when they contact either semiconductive or conductive nanotubes, indicating a strong electronic coupling to both. Theoretical simulations predict a favorable energy level alignment within these complexes, suggesting a photoinduced electron transfer from dots to nanotubes, which is a process of high functional interest. Femtosecond transient absorption confirms indeed an ultrafast (<100 fs) electron transfer independent of nanotubes being conductive or semiconductive in nature, followed by a much slower back electron transfer (≈60 ps) from the nanotube to the carbon dots. The high degree of charge separation and delocalization achieved in these nanohybrids entails significant photocatalytic properties, as we demonstrate by the reduction of silver ions in solution. The results are very promising in view of using these “all-carbon” nanohybrids as efficient light harvesters for applications in artificial photocatalysis and photosynthesis