Efecto de la emulsificación sobre la actividad antimicrobiana del carvacrol

Este trabajo se basa en la emulsificación del carvacrol para su incorporación a jugos con el objetivo de retener su actividad antimicrobiana y mejorar la estabilidad del aceite en sistemas acuosos. El carvacrol se emulsificó (CA-E) utilizando capsul® (emulsión1:2) y la actividad antimicrobiana se determinó sobre Escherichia coli y Lactobacillus plantarum. El efecto combinado de CA-E y la reducción del pH a 4,5 se evaluó en diferentes jugos. La emulsión no afectó la sensibilidad de L. plantarum al carvacrol; sin embargo, E. coli presentó mayor concentración mínima inhibitoria. Los tratamientos combinados incrementaron el efecto, 0,5 µL/mL CA-E aumentó desde 0,2 a 2,1 reducciones log de E. coli. La emulsión de carvacrol (1,0 µL/mL) inactivó exitosamente a E. coli en jugos de manzana y naranja, alcanzando niveles indetectables (<1 log UFC/mL). La eficacia de la emulsión de carvacrol aumentó por la acidificación, permitiendo su uso en bajas dosis en alimentos ácidos, constituyendo una alternativa para múltiples aplicaciones en alimentos.This work focuses on the emulsification of carvacrol for its incorporation into juices with the aim of retaining antimicrobial activity while enhancing the stability of the oil in aqueous systems. Carvacrol was emulsified (CA-E) using capsul® (1:2 emulsion) and its antimicrobial activity was determined on Escherichia coli and Lactobacillus plantarum. The combined effect of CA-E and pH reduction to 4.5 was assessed on different juices. The sensitivity of L. plantarum to carvacrol was not affected by emulsification, whereas E. coli presented higher minimal inhibitory concentrations. Combined treatments improved the effect: 0.5 µL/mL CA-E increased from 0.2 to 2.1 log reductions of E. coli. Carvacrol emulsion (1.0 µL/mL) successfully inactivated E. coli in apple and orange juices, attaining undetectable levels (<1 log CFU/mL). The efficacy of carvacrol emulsion was improved by acidification; therefore, its incorporation at low doses in acidic foods may be a useful alternative for multiple applications.Fil: Char, Cielo Dolores. Universidad de Chile; Chile. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cisternas, Lorena. Universidad de Chile; ChileFil: Perez, Francisco. Universidad de Chile; ChileFil: Guerrero, Sandra N.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Análisis de un modelo tutorial en práctica docente fundamentado en la TSD

La tutoría en práctica docente se vuelve crucial porque en ella el estudiante para profesor toma decisiones sobre el diseño, la gestión, la sistematización, la escritura, entre otros, en tanto, este conocimiento práctico generado en el ejercicio de la enseñanza le sirve para apoyar su propio juicio. En la tutoría son importantes las manifestaciones conscientes o no de las aversiones o preferencias de los EPPs por la resolución de problemas, en tanto, si el modelo propiciado por el profesor favorece el autoestima y la intuición, genera autonomía en la toma de decisiones. Este hecho ha servido para que los EPPs entiendan que el pensamiento reflexivo se centra en sus propios juicios y en sus resultados

The Site-Diluted Ising Model in Four Dimension

In the literature, there are five distinct, fragmented sets of analytic predictions for the scaling behaviour at the phase transition in the random-site Ising model in four dimensions. Here, the scaling relations for logarithmic corrections are used to complete the scaling pictures for each set. A numerical approach is then used to confirm the leading scaling picture coming from these predictions and to discriminate between them at the level of logarithmic corrections.Comment: 15 pages, 5 ps figures. Accepted for publication in Phys. Rev.

Detection of new eruptions in the Magellanic Clouds LBVs R 40 and R 110

We performed a spectroscopic and photometric analysis to study new eruptions in two luminous blue variables (LBVs) in the Magellanic Clouds. We detected a strong new eruption in the LBV R40 that reached $V \sim 9.2$ in 2016, which is around $1.3$ mag brighter than the minimum registered in 1985. During this new eruption, the star changed from an A-type to a late F-type spectrum. Based on photometric and spectroscopic empirical calibrations and synthetic spectral modeling, we determine that R\,40 reached $T_{\mathrm{eff}} = 5800-6300$~K during this new eruption. This object is thereby probably one of the coolest identified LBVs. We could also identify an enrichment of nitrogen and r- and s-process elements. We detected a weak eruption in the LBV R 110 with a maximum of $V \sim 9.9$ mag in 2011, that is, around $1.0$ mag brighter than in the quiescent phase. On the other hand, this new eruption is about $0.2$ mag fainter than the first eruption detected in 1990, but the temperature did not decrease below 8500 K. Spitzer spectra show indications of cool dust in the circumstellar environment of both stars, but no hot or warm dust was present, except by the probable presence of PAHs in R\,110. We also discuss a possible post-red supergiant nature for both stars

Modelos de calidad aplicados al servicio de mediación en México

This article is a research that has a purely qualitative approach, part of a non-experimental design, under a cross-sectional documentary-bibliographic level. Its general objective is to analyze the main quality evaluation models and to define which of them has been applied to evaluate the mediation service in Mexico. After reviewing the literature and the documentary analysis it was determined that: The main national and international quality models have not yet been applied to evaluate the mediation service, since they are focused on assessing a general context such as the traditional justice system and other items related to the marketing of products and services. However, it was determined that the quality of the mediation service has been evaluated by standardized models developed by some academic research. It is concluded that in Mexico there is a need to implement rigorous and standardized models to evaluate the mediation service, with the aim of obtaining a national and international certification that ratifies the institutions that meet the quality standards.El presente artículo es una investigación que posee un enfoque meramente cualitativo, parte de un diseño no experimental, bajo un nivel documental-bibliográfico trasversal. Tiene por objetivo general analizar los principales modelos de evaluación de la calidad y definir cuál de ellos ha sido aplicado para evaluar el servicio de mediación en México. Tras la revisión de la literatura y el análisis documental se determinó que: Los principales modelos de calidad de índole nacional e internacional, aún no han sido aplicados para evaluar el servicio mediación, ya que están enfocados en evaluar un contexto general como lo es el sistema de justicia tradicional y otros rubros relacionados a la comercialización de productos y servicios. Sin embargo, se determinó que la calidad del servicio de mediación ha sido evaluada por modelos estandarizados, desarrollados por algunas investigaciones académicas. Se concluye que en México existe la necesidad de implementar modelos rigurosos y estandarizados encargados de evaluar al servicio de mediación, con la finalidad de obtener una certificación nacional e internacional que ratifique a las instituciones que cumplen con los estándares de calidad

Exploring the Relationship Between Immediacy Behaviors and Student Motivation in Engineering Classrooms: Immediacy as a Cause of Motivation

Instructor immediacy is an essential characteristic of effective instructors. Although instructional communication has done extensive research on the impact of immediacy behaviors on students, there is little available research observing immediacy behaviors as predictors of motivation on engineering students. As a result, this study examined the impact of engineering instructors’ use of immediacy behaviors on engineering students’ motivation. The results indicated that verbal immediacy predicted engineering student motivation. The thematic analysis revealed that when students perceived their instructors as helpful, students’ motivation to learn and ask more questions increased. The thematic analysis also observed that when instructors seemed unapproachable, students were less likely to engage with them. These findings present valuable insight for engineering educators on how their immediacy behaviors can both positively and negative affect student motivation and possible retention

What sets the magnetic field strength and cycle period in solar-type stars?

Two fundamental properties of stellar magnetic fields have been determined by observations for solar-like stars with different Rossby numbers (Ro), namely, the magnetic field strength and the magnetic cycle period. The field strength exhibits two regimes: 1) for fast rotation it is independent of Ro, 2) for slow rotation it decays with Ro following a power law. For the magnetic cycle period two regimes of activity, the active and inactive branches, also have been identified. For both of them, the longer the rotation period, the longer the activity cycle. Using global dynamo simulations of solar like stars with Rossby numbers between ~0.4 and ~2, this paper explores the relevance of rotational shear layers in determining these observational properties. Our results, consistent with non-linear alpha^2-Omega dynamos, show that the total magnetic field strength is independent of the rotation period. Yet at surface levels, the origin of the magnetic field is determined by Ro. While for Ro<1 it is generated in the convection zone, for Ro>1 strong toroidal fields are generated at the tachocline and rapidly emerge towards the surface. In agreement with the observations, the magnetic cycle period increases with the rotational period. However, a bifurcation is observed for Ro~1, separating a regime where oscillatory dynamos operate mainly in the convection zone, from the regime where the tachocline has a predominant role. In the latter the cycles are believed to result from the periodic energy exchange between the dynamo and the magneto-shear instabilities developing in the tachocline and the radiative interior.Comment: 43 pages, 14 figures, accepted for publication in The Astrophysical Journa