Synthesis and Magnetic Characterization of Graphite-Coated Iron Nanoparticles

Graphite-coated iron nanoparticles were prepared from magnetite nanoparticles by chemical vapour deposition (CVD) under methane and hydrogen atmosphere. After being purified from carbon excess, graphite-coated iron nanoparticles were tested for morphological and magnetic properties. It was found that, during the thermal process, magnetite nanoparticles 6 nm in size coalesce and transform into graphite-coated iron 200 nm in size, as revealed by scanning electron microscopy (SEM). Raman characterization assessed that high-quality graphite coats the iron core. Magnetic measurements revealed the phase change (magnetite to iron) as an increase in the saturation magnetization from 50 to 165 emu/g after the CVD process

Factors that influence French consumer satisfaction in the preference for Chilean avocados (Persea americana Mill.)

Most avocados consumed in France come from Peru or Chile. French suppliers vary based on the season; however, Chile is the main supplier of avocados during the winter season. The aim of this study is to analyze the key variables that influence French consumer satisfaction in the preference for Chilean avocados.This is substantiated using an exploratory multivariate analysis, which was performed on a causal model comprised of endogenous constructs: perceived extrinsic and intrinsic quality, perceived risk and perceived value. The sample consists of 346 French consumers of Chilean avocados in supermarkets of the Auvergne-Rhône-Alpes region. The main results show that the risk perceived by French consumers can only be related to the perceived extrinsic quality of the product. On the other hand, both perceived intrinsic and extrinsic quality are directly related to perceived value. Finally, it is concluded that French consumer satisfaction in the preference for Chilean avocados can be explained by the variables perceived intrinsic quality, perceived extrinsic quality and perceived value

Suitability of a three-dimensional model to measure empathy and its relationship with social and normative adjustment in Spanish adolescents: a cross-sectional study

Objectives: (1) To examine the psychometric properties of the Basic Empathy Scale (BES) with Spanish adolescents, comparing a two and a three-dimensional structure;(2) To analyse the relationship between the three-dimensional empathy and social and normative adjustment in school. Design: Transversal and ex post facto retrospective study. Confirmatory factorial analysis, multifactorial invariance analysis and structural equations models were used. Participants: 747 students (51.3% girls) from Cordoba, Spain, aged 12–17 years (M=13.8; SD=1.21). Results: The original two-dimensional structure was confirmed (cognitive empathy, affective empathy), but a three-dimensional structure showed better psychometric properties, highlighting the good fit found in confirmatory factorial analysis and adequate internal consistent valued, measured with Cronbach’s alpha and McDonald’s omega. Composite reliability and average variance extracted showed better indices for a three-factor model. The research also showed evidence of measurement invariance across gender. All the factors of the final three-dimensional BES model were direct and significantly associated with social and normative adjustment, being most strongly related to cognitive empathy. Conclusions: This research supports the advances in neuroscience, developmental psychology and psychopathology through a three-dimensional version of the BES, which represents an improvement in the original two-factorial model. The organisation of empathy in three factors benefits the understanding of social and normative adjustment in adolescents, in which emotional disengagement favours adjusted peer relationships. Psychoeducational interventions aimed at improving the quality of social life in schools should target these components of empathy

Green Routes for Graphene Oxide Reduction and Self- Assembled Graphene Oxide Micro- and Nanostructures Production

Graphene-derived materials are currently studied because of their actual and projected applications. Among them, graphene oxide (GO) promises for outstanding applications as it can be prepared at large scale by simple, scalable, and low-cost techniques. The existent chemical methods based on the graphite exfoliation (phase solution and Hummers based) produce highly functionalized graphene, i.e., GO-like materials that converts into reduced GO (rGO) after a reduction treatment. The present work presents the current scenario on the GO green reduction methods, on the development of hierarchical carbon-based structures by the self-assembly of GO sheets at interfaces, and on rGO-based hybrid nanocomposites. It is worth noting that, to date, the production and application of graphene-related materials are the fastest-growing research areas

Producto MAGIC GLOVES

El proyecto se lleva a cabo con el fin de incentivar el emprendimiento sea cual fuere el producto o servicio, para este caso el esfuerzo se ha centrado en los guantes de marca Magic Gloves, viendo la necesidad de un producto que haga más práctico llevar a cabo las labores de aseo en los hogares

CdTe Thin Films: Deposition Techniques and Applications

The II-IV semiconductor compound, CdTe, has suitable electrical and optical properties as photovoltaic and high-energy radiation sensor material. As an absorber material for thin-film-based solar cells, CdTe holds the potentiality to fabricate high-efficiency solar cells by means of low-cost technologies. This chapter presents a comprehensive review on the CdTe thin-film deposition techniques as well as on the several configurations for the solar cell structures that have led the best efficiency conversion. Current CdTe thin-film deposition techniques include sputtering, close spaced vapor transport (CSVT), chemical spray pyrolysis, and electrodeposition. These techniques have easily been adapted to deposit polycrystalline CdTe films on various flexible and rigid substrates. In regard to the device structure configuration, a variety of partner materials (transparent contact, optical window, buffer layer) were tested, and CdTe film thickness was varied to develop opaque and semitransparent devices by some techniques mentioned above. In this chapter, we will discuss about each technique used for CdTe thin-film deposition as well as its advantages and disadvantages

Empleo de un modelo de crecimiento y rendimineto para la deteminación de la edad óptima de rotación de Pinus Caribaea var. Hondurensis creciendo en la región oriental de Colombia

This study was developed in order to generate to contribute to the forest plantations planning in Colombia. The objective was to adjust volume and basal area growth and yield projection models in order to detemine the optimal rotation age of Pinus caribaea growing in site indexes 18 and 22. Models were adjusted through the biological criterion of mean annual increment maximization and the economical criteria of both present net value and soil expectation value maximization. The optimal rotation age was between 10 and 13 years. The longest rotations were obtained through the biological criterion and shortest with the economic criteria.Este estudio se desarrolló con el fin de generar heramientas que contribuyan a la planificación de las plantaciones forestales en Colombia. El objetivo fue ajustar modelos de proyección del crecimiento y rendimiento en área basal y volumen para determinar la edad ótima de rotación de Pinus caribaea que crece en índices de sitio 18 y 22. Los modelos se ajustaron a través del criterio biológico de maximización del incremento medio anual y de los criterios criterios económicos de maximización del valor actual neto y del valor potencial del suelo. La rotación optima se determinó entre 10 y 13 años de edad, las rotaciones más largas se obtuvieron con le criterio biológico y las más cortas con los económicos

How much do adolescents cybergossip?: Scale development in validation in Spain and Colombia

Cybergossip is the act of two or more people making evaluative comments via digital devices about somebody who is not present. This cyberbehavior affects the social group in which it occurs and can either promote or hinder peer relationships. Scientific studies that assess the nature of this emerging and interactive behavior in the virtual world are limited. Some research on traditional gossip has identified it as an inherent and defining element of indirect relational aggression. This paper adopts and argues for a wider definition of gossip that includes positive comments and motivations. This work also suggests that cybergossip has to be measured independently from traditional gossip due to key differences when it occurs through ICT. This paper presents the Colombian and Spanish validation of the Cybergossip Questionnaire for Adolescents (CGQ-A), involving 3,747 high school students (M = 13.98 years old, SD = 1.69; 48.5% male), of which 1,931 were Colombian and 1,816 were Spanish. Test models derived from item response theory, confirmatory factor analysis, content validation, and multi-group analysis were run on the full sample and subsamples for each country and both genders. The obtained optimal fit and psychometric properties confirm the robustness and suitability of a one-dimensional structure for the cybergossip instrument. The multi-group analysis shows that the cybergossip construct is understood similarly in both countries and between girls and boys. The composite reliability ratifies convergent and divergent validity of the scale. Descriptive results show that Colombian adolescents gossip less than their Spanish counterparts and that boys and girls use cybergossip to the same extent. As a conclusion, this study confirmes the relationship between cybergossip and cyberbullying, but it also supports a focus on positive cybergossip in psychoeducational interventions to build positive virtual relationships and prevent risky cyberbehaviors

Fabrication and photophysical studies of CdTe quantum-dots dispersed in SiO2 sonogel optical-glasses

The catalyst-free sonogel route has been implemented to fabricate highly pure SiO2 glasses as host materials for CdTe quantum dot nanocrystals synthesized in aqueous solution. Developed CdTe-based inorganic–inorganic hybrid composites exhibited rigid bulk structures with controllable geometrical shapes and dopant concentrations, allowing the control of the optical properties in the solid-state confinement. Comprehensive linear and nonlinear photophysical characterizations were performed according to UV–vis absorbance, Raman and photoluminescent spectroscopies; the linear refractive indices of highly/lowly CdTe-doped samples were also estimated according to the Brewster angle technique. Since the hybrid glasses are amorphous in nature, the cubic nonlinear optical activity of these composites has been tested via the Z-Scan technique. Results show that the CdTe quantum dots were homogeneously embedded within the SiO2-sonogel matrix with only small guest–host molecular interactions and preserving their strong photoluminescent properties; thus providing advanced solid-state heterostructured nanocomposite materials suitable for current technological photonic applications