Color Engineering of Silicon Nitride Surfaces to Characterize the Polydopamine Refractive Index

A simple methodology to generate polydopamine (PDA) surfaces featured with color due to thin-film interference phenomena is presented. It is based on depositing ultra-thin films of polydopamine on a Si/Si 3 N 4 wafer that exhibits an interferential reflectance maximum right at the visible/UV boundary (∼400 nm). Therefore, a small deposit of PDA modifies the optical path, in such manner that the wavelength of the maximum of reflectance red shifts. Because the human eye is very sensitive to any change of the light spectral distribution at the visible region, very small film thickness changes (∼30 nm) are enough to notably modify the perceived color. Consequently, a controlled deposit of PDA, tune the color along the whole visible spectrum. Additionally, good quality of PDA deposits allowed us to determine the refractive index of polydopamine by ellipsometry spectroscopy. This data can be crucial in confocal skin microscopic techniques, presently used in diagnosis of skin tumors.Fil: Vega Moreno, Milena Amparo. Universidad de Salamanca; EspañaFil: Martín del Valle, Eva M.. Universidad de Salamanca; EspañaFil: Perez, Maximiliano Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Tecnológica Nacional. Facultad Regional Haedo; ArgentinaFil: Pecharromán, Carlos. Consejo Superior de Investigaciones Científicas. Instituto de Ciencia de los Materiales de Barcelona; EspañaFil: Marcelo, Gema. Universidad de Salamanca; Españ

La coordinación de las aproximaciones en la comprensión del concepto de límite cuando los estudiantes para profesor anticipan respuestas de estudiantes

El objetivo de este estudio es examinar en qué medida la identificación de la coordinación de las aproximaciones en el dominio y el rango de una función es considerado un avance conceptual (KDU en Simon, 2006) en la comprensión del concepto de límite de una función por futuros profesores. Veinticinco estudiantes para profesor de matemáticas anticiparon respuestas de estudiantesde bachillerato a problemas sobre el límite de una función que mostraban distintas características de la comprensión y propusieron problemas para apoyar el progreso conceptual de los estudiantes. Los resultados muestran que identificar la coordinación de las aproximaciones en el dominio y el rango como KDU permitió a los estudiantes para profesor considerar progresiones en el aprendizaje sobre las que apoyar sus propuestas de enseñanza.The aim of this study is to examine to what extent the identification of the coordination of approximations in the domain and in the range is considered a Key Developmental Understanding (KDU in Simon, 2006) by prospective teachers. 25 prospective secondary school mathematics teachers anticipated high school students’ answers to problems about the limit of a function showing different characteristics of understanding and proposed problems that would support students’ conceptual progress. Results show that identifying the coordination of the approximations in the domain and in the range as KDU allowed prospective teachers to consider progressions in students’ learning in order to support their teaching decisions.El objetivo de este estudio es examinar en qué medida la identificación de la coordinación de las aproximaciones en el dominio y el rango de una función es considerado un avance conceptual (KDU en Simon, 2006) en la comprensión del concepto de límite de una función por futuros profesores. Veinticinco estudiantes para profesor de matemáticas anticiparon respuestas de estudiantesde bachillerato a problemas sobre el límite de una función que mostraban distintas características de la comprensión y propusieron problemas para apoyar el progreso conceptual de los estudiantes. Los resultados muestran que identificar la coordinación de las aproximaciones en el dominio y el rango como KDU permitió a los estudiantes para profesor considerar progresiones en el aprendizaje sobre las que apoyar sus propuestas de enseñanza

A knowledge management-based conceptual model to improve the level of utilization of ICTs in Mexican SMEs

The current commercial context for the Small and medium-sized enterprises (SMEs) is an ever-changing environment that is strongly influenced by the information and communication technologies (ICTs). This has led enterprises to implement these technologies as supportive tools for their business processes. Nevertheless, a vast number of SMEs have not obtained favorable results in implementing ICTs, since the lack of knowledge about the potential and application of these technologies has made this technological implementation activity prevail as an action oriented to the simple acquisition of equipment and informatic systems with a short-term vision without considering a business strategy. The aim of this paper is to perform a literature review that shows evidence of the low utilization of ICTs in SMEs, particularly in the Mexican environment, which leads to proposing a different approach where enterprises consider Knowledge Management (KM) in the implementation of the informatic technology, leading to a conceptual model to ensure human, organizational and relational capital provide the proper capabilities to complement a strategy that implies carrying out a correct acquisition and application of knowledge that contributes to improving the utilization of ICTs in the business processes

Role of Sterile Neutrino Warm Dark Matter in Rhenium and Tritium Beta Decays

Sterile neutrinos with mass in the range of one to a few keV are important as extensions of the Standard Model of particle physics and are serious dark matter (DM) candidates. This DM mass scale (warm DM) is in agreement with both cosmological and galactic observations. We study the role of a keV sterile neutrino through its mixing with a light active neutrino in Rhenium 187 and Tritium beta decays. We pinpoint the energy spectrum of the beta particle, 0 < T_e < (Q_{beta} - m_s), as the region where a sterile neutrino could be detected and where its mass m_s could be measured. This energy region is at least 1 keV away rom the region suitable to measure the mass of the light active neutrino, located near the endpoint Q_{beta} . The emission of a keV sterile neutrino in a beta decay could show up as a small kink in the spectrum of the emitted beta particle. With this in view, we perform a careful calculation of the Rhenium and Tritium beta spectra and estimate the size of this perturbation by means of the dimensionless ratio R of the sterile neutrino to the active neutrino contributions. We comment on the possibility of searching for sterile neutrino signatures in two experiments which are currently running at present, MARE and KATRIN, focused on the Rhenium 187 and Tritium beta decays respectively.Comment: 16 pages, 10 figures. Version to appear in Nucl. Phys. B. Results and conclusions unchange

Role of Sterile Neutrino Warm Dark Matter in Rhenium and Tritium Beta Decays

Sterile neutrinos with mass in the range of one to a few keV are important as extensions of the Standard Model of particle physics and are serious dark matter (DM) candidates. This DM mass scale (warm DM) is in agreement with both cosmological and galactic observations. We study the role of a keV sterile neutrino through its mixing with a light active neutrino in Rhenium 187 and Tritium beta decays. We pinpoint the energy spectrum of the beta particle, 0 < T_e < (Q_{beta} - m_s), as the region where a sterile neutrino could be detected and where its mass m_s could be measured. This energy region is at least 1 keV away rom the region suitable to measure the mass of the light active neutrino, located near the endpoint Q_{beta} . The emission of a keV sterile neutrino in a beta decay could show up as a small kink in the spectrum of the emitted beta particle. With this in view, we perform a careful calculation of the Rhenium and Tritium beta spectra and estimate the size of this perturbation by means of the dimensionless ratio R of the sterile neutrino to the active neutrino contributions. We comment on the possibility of searching for sterile neutrino signatures in two experiments which are currently running at present, MARE and KATRIN, focused on the Rhenium 187 and Tritium beta decays respectively.Comment: 16 pages, 10 figures. Version to appear in Nucl. Phys. B. Results and conclusions unchange

Student mentoring program at the Faculty of Pharmacy, University of Seville (2006/07 - present): SWOT analysis carried out by mentor students

El “Programa de Alumnos Tutores” (LCC, Facultad de Farmacia US) se viene realizando ininterrumpidamente desde 2006/07 hasta la actualidad. Propósito: tutela de alumnos de nuevo ingreso por parte de alumnos de cursos superiores (AATT) bajo la supervisión de Profesores Tutores. Pretende generar una actitud responsable en los AATT y favorecerles el desarrollo de habilidades sociales. El objetivo de este trabajo es recoger las opiniones de los AATT (algunos comenzaron en ediciones anteriores y continúan desinteresadamente). Se aborda mediante un análisis DAFO. Conclusión: se han detectado factores estratégicos críticos, para una vez identificados, usarlos y apoyar en ellos la marcha del “Programa de Alumnos Tutores”, consolidando las fortalezas, minimizando las debilidades, aprovechando las ventajas de las oportunidades, y eliminando o reduciendo las amenazas.The "Student Mentor Program" (Faculty of Pharmacy, US) has been running since 2006/07 – to present. Purpose: to mentor new students by senior students (Mentor Students) under the supervision of mentor professors. It aims to generate a responsible attitude in students and tutors to encourage the development of social skills. Objective: To collect the views of mentor students (some started in previous years and continue to selflessly), through a SWOT analysis. Conclusion: it has been found critical strategic factors. It intends to use these factors for strengthening the "Student Mentor Program"

Self-dual Ginzburg-Landau vortices in a disk

We study the properties of the Ginzburg-Laundau model in the self-dual point for a two-dimensional finite system . By a numerical calculation we analyze the solutions of the Euler-Lagrange equations for a cylindrically symmetric ansatz. We also study the self-dual equations for this case. We find that the minimal energy configurations are not given by the Bogomol'nyi equations but by solutions to the Euler Lagrange ones. With a simple approximation scheme we reproduce the result of the numerical calculation.Comment: 8 pages, 4 figures, RevTex macro

Agentes de onicomicosis en manos y pies en Valdivia (Chile)

Se estudiaron 78 muestras de uñas de manos y pies de 74 pacientes con diagnóstico de onimicosis   Para la obtención de la muestra se raspó la lámina interna de la uña, excepcionalmente la lámina externa y se efectuó el examen microscopico directo ya sea en KOH-20% -tinta Parker 51 azul permanente o con KOH-20% - Chloroback E. Todas las muestras fueron sembradas en agarSabouraud dextrosado, agar Lactrimel y agar selectivo para dermatofitos (DIM) e incubadas a 28°C por 10-15 días.   De las muestras estudiadas, en el 79.5% se observaron hongos al examen microscópico directo, aislándose estos en el 61.5% de los cultivos.   La frecuencia de agentes de onimicosis fue: C .albicans (43.75%). T. rubrum (31.25%) y T.mentagrophytes (10.42%). C. albicans se aisló en el 70.8% de las onimicosis en manos de mujeres.   T.rubrum se aisló en un 50 y 25% de hombres y mujeres respectivamente. En pie se aisló en el 52,9% y en mano en un 19.3% .   S. brevicaulis fue aislado en un solo caso

Synthesis and characterization of nanocrystalline cellulose derived from Pineapple peel residues

Pineapple peel biomass was used as raw material for nanocellulose extraction. The raw material is a residue from the Costa Rican fruit industry. The nanocellulose was obtained by a two-step hydrolysis process. Firstly, the cellulose was hydrolyzed with HCl to obtain microcrystalline cellulose. In the second step, the hydrolysis was carried out using H2SO4 to obtain smaller fragments and decrease the lignin content. A time-dependent study was carried out to determine the particle size decrease depending on the contact time with the H2SO4. The chemical, thermal and morphological properties were analyzed by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), dynamic light scattering (DLS), zeta potential, atomic force microscopy (AFM) and scanning electron microscopy (SEM). The nanofiber-like cellulose was obtained after 60 minutes of exposure to 65 wt% H2SO4

Comparative study of electrical and rheological properties of different solutions used in endoscopic mucosal resection

Background and Aim: The study of electrical and rheological properties of solutions to carry out endoscopic resection procedures could determinate the best candidate. An ex vivo study with porcine stomachs was conducted to analyze electrical resistivity (R) and rheological properties (temperature, viscosity, height and lasting of the cushion) of different substances used in these techniques. Methods: Tested solutions were: 0.9% saline (S), platelet-rich plasma (PRP), Gliceol (GC), hyaluronic acid 2% (HA), Pluronic-F127 20% (PL), saline with 10% glucose (GS), Gelaspan (GP), Covergel-BiBio (TB) and PRP with TB (PRP+TB). Measurements of electrical and rheological properties were done at 0, 15, 30, 45 and 60 min after submucosal injection. Results: Solutions showed a wide variability of transepithelial R after submucosal injection. Substances able to maintain the highest R 60 min postinjection were TB (7 × 10 Ω), HA (7 × 10 Ω) and PL (7 × 10 Ω). Protective solutions against deep thermal injury (Tª lower than 60°C) were PL (47.6°C), TB (55°C) and HA (56.63°C). Shortest time to carry out resections were observed with GC (17.66″), PRP (20.3″) and GS (23.45″). Solutions with less cushion decrease (<25%) after 60 min were TB (11.74%), PL (18.63%) and PRP (22.12%). Conclusions: Covergel-BiBio, PL and HA were the best solutions with long-term protective effects (transepithelial R, lower thermal injury and less cushion decrease). Solutions with quicker resection time were GC, PRP and GS