Modeling Optical and Electronic Properties of Silica Nano-Clusters in Silicon Rich Oxide Films

Quantum effects are very important in nano scale systems such as molecules and clusters constituted of particles from a few to hundreds or a few thousands of atoms. Their optical and electronic properties are often dependent on the size of the systems and the way in which the atoms in these molecules or clusters are bonded. Generally, these nano-structures display optical and electronic properties significantly different of the bulk materials. Silica agglomerates expected in Silicon Rich Oxide (SRO) films have optical properties, which depend directly on size, and their rationalization can lead to new applications with a potential impact on many fields of science and technology. On the other hand, the room temperature photoluminescence (PL) of Si : SiO2 or Si : SiOx structures usually found in SRO has recently generated an enormous interest due to their possible applications in optoelectronic devices. However, the understanding of the emission mechanism is still under debate. In this research, we employed the Density Functional Theory with a functional B3LYP and a basis set 6-31 G* to calculate the electronic and optical properties of molecules and clusters of silicon dioxide. With the theoretical calculation of the structural and optical properties of silicon dioxide clusters is possible to evaluate the contribution of silica in the luminescent emission mechanism experimentally found in thin SRO films. It was found that silica contribution to the luminescent phenomenon in SRO thin films is less important than that of the silicon monoxide agglomerates because the number of silica structures, which may show emission in the visible spectrum, is much lower [1], compared to the number of silicon monoxide structures which emit in this region. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3192

Dependence of exchange anisotropy and coercivity on the Fe–oxide structure in oxygen-passivated Fe nanoparticles

3 pages, 5 figures.Ultrafine Fe particles have been prepared by the inert gas condensation method and subsequently oxygen passivated. The as-obtained particles consist in an Fe core surrounded by an amorphous Fe-oxide surface layer. The antiferromagnetic character of the Fe-oxide surface induces an exchange anisotropy in the ferromagnetic Fe core when the system is field cooled. Samples have been heat treated in vacuum at different temperatures. Structural changes of the Fe–O layer have been monitored by x-ray diffraction and transmission electron microscopy. Magnetic properties as coercivity, hysteresis loop shift, and evolution of magnetization with temperature have been analyzed for different oxide crystallization stages. A decrease of the exchange anisotropy strength is reported as the structural disorder of the surface oxide layer is decreased with thermal treatment.Peer reviewe

Integrating local environmental data and information from non-driven citizen science to estimate jellyfish abundance in Costa del Sol (southern Spain)

Tourism, fishing and aquaculture are key economic sectors of Costa del Sol (southern Iberian Peninsula). The management of these activities is sometimes disturbed by the onshore arrival and stranding of jellyfish swarms. In the absence data on the occurrence of these organisms, it may be interesting to explore data from non-driven systems, such as social networks. The present study show how data in text format from a mobile app called Infomedusa can be processed and used to model the relationship between estimated abundance of jellyfish on the beaches and local environmental conditions. The data retrieved from this app using artificial intelligence procedures (transition network or TN algorithm), were used as input for GAM models to estimate the abundance of jellyfish based on wind speed and direction. The analysis of data provided by Infomedusa indicated that only 30.39% of messages provided by the users had information about absence/presence of jellyfishes in the beaches. On the other hand, the TN processing capacity showed an accuracy level to discriminate messages with information on absence/presence of jellyfish slightly higher than 80%. GAM models considering the wind direction and speed of previous day explained between 37% and 77% of the variance of jellyfish abundance estimate from Infomedusa data. In conclusion, this approach may contribute to the development of a system for predicting the onshore arrival of jellyfish in the Costa del Sol.Versión del edito

A general perspective of the characterization and quantification of nanoparticles: Imaging, spectroscopic, and separation techniques

This article gives an overview of the different techniques used to identify, characterize, and quantify engineered nanoparticles (ENPs). The state-of-the-art of the field is summarized, and the different characterization techniques have been grouped according to the information they can provide. In addition, some selected applications are highlighted for each technique. The classification of the techniques has been carried out according to the main physical and chemical properties of the nanoparticles such as morphology, size, polydispersity characteristics, structural information, and elemental composition. Microscopy techniques including optical, electron and X-ray microscopy, and separation techniques with and without hyphenated detection systems are discussed. For each of these groups, a brief description of the techniques, specific features, and concepts, as well as several examples, are described.Junta de Andalucía FQM-5974CEI-Biotic Granada CEI2013- MP-1

Seroreversion of IgG anti-HEV in HIV cirrhotic patients: A long-term multi-sampling longitudinal study

The aim of our study was to evaluate HEV antibody kinetics in HIV/HCV-coinfected patients with cirrhosis. A longitudinal retrospective study was designed. Patients were followed up every 6 months; anti-HEV IgG and IgM antibodies levels and HEV-RNA by qPCR were analysed. The prevalence and incidence of every HEV infection marker were calculated. The kinetics of anti-HEV IgG and IgM during the follow-up were evaluated. Seventy-five patients comprised the study population. The seroprevalence observed was 17.3%. None showed IgM antibodies or HEV-RNA at baseline. None showed detectable HEV viral load during the study period. After a median follow-up of 5.1 years, two of 62 seronegative patients (3.2%) seroconverted to IgG antibody. The incidence for IgM was 2.7%. Of the 13 patients with IgG seropositivity at baseline, five (38.5%) seroreverted. Meanwhile, of the two patients who exhibited IgM positivity during the study, one (50%) showed intermittent positivity. We found that HEV seropositivity is common in HIV/HCV-coinfected cirrhotic patients. A remarkable rate of IgG seroreversions and IgM intermittence was found, limiting the use of antibodies for the diagnosis of HEV infection in this population

Competencia emocional en docentes de Infantil y Primaria y estudiantes universitarios de los Grados de Educación Infantil y Primaria

This descriptive-correlational study assesses the emotional competence of Preschool and Elementary School teachers and university students of Preschool and Elementary School Education Degrees. There was a subsample of 92 teachers and another of 290 students. Emotional competence was operationally defi ned on the basis of two indicators: metamood states and cognitive-affective empathy. The results reveal that the level of development in most of the components of emotional competence studied are higher for those with more experience (teachers vs. students) and for those with some degree of emotional training, which indirectly supports the modifi - ability of emotional competence.El estudio, descriptivo-correlacional, evalúa la competencia emocional de docentes de Infantil y Primaria y de estudiantes universitarios de los Grados de Educación Infantil y Primaria. Se contó con una submuestra de 92 docentes y otra de 290 estudiantes. La competencia emocional se defi nió operacionalmente a partir de dos indicadores: meta- estados de ánimo y empatía cognitiva-afectiva. Los resultados revelan que el nivel de desarrollo en la mayoría de los componentes de la competencia emocional estudiados son superiores en quienes tienen mayor experiencia (docentes vs. estudiantes) y poseen algún grado de formación emocional, lo que indirectamente avala la modifi cabilidad de la competencia emocional