Caracterización reológica de una suspoemulsión comercial para uso agroquímico

Se estudian las propiedades reológicas de una suspoemulsión comercial para uso agroquímico. Se comparan los resultados obtenidos mediante curvas de flujo y ensayos en cizalla oscilatoria de baja amplitud para cinco temperaturas distintas en el intervalo de 5 a 25ºC. Las curvas de flujo, ponen de manifiesto que la suspoemulsión se caracteriza por presentar un comportamiento pseudoplástico, menos acusado a medida que aumenta la temperatura, que se ajusta al modelo de Sisko. Barridos de esfuerzo realizados a 0,1Hz permiten determinar el reducido rango viscoelástico lineal de la suspoemulsión, que depende de la temperatura. Los espectros mecánicos, entre 3Hzy 0,01 Hz, revelan que el sistema manifiesta propiedades viscoelásticas con un comportamiento típico de gel débil. La aparición de un mínimo en el valor de G” respecto a la frecuencia ha permitido estimar el modulo plateau, el cual desciende con el aumento de temperatura según una ecuación tipo Arrhenius. Aun así, la suspoemulsión presenta un carácter elástico que favorece su estabilidad física con el tiempo de almacenamiento. Se ha demostrado además que el sistema no sigue la regla de Cox-Merz

Relationship between HLB Number and Predominant Destabilization Process in Microfluidized Nanoemulsions Formulated with Lemon Essential Oil

Lemon essential oil (LEO) is associated with a multitude of health benefits due to its anticancer, antioxidant, antiviral, anti-inflammatory and bactericidal properties. Its drawback is that it is very sensitive to oxidation by heat. For this reason, researchers are increasingly investigating the use of LEO in nanoemulsions. In this work, we used laser diffraction, rheology and multiple light scattering techniques to study the effects of different HLB numbers (indicating different mixtures of Tween 80 and Span 20) on the physical stability of nanoemulsions formulated with LEO. We found that different HLB numbers induced different destabilization mechanisms in these emulsions. An HLB number lower than 12 resulted in an Ostwald ripening effect; an HLB number higher than 12 resulted in coalescence. In addition, all the developed nanoemulsions exhibited Newtonian behavior, which could favor the mechanism of creaming. All emulsions exhibited not only a growth in droplet size, but also a creaming with aging time. These findings highlight the importance of selecting the right surfactant to stabilize nanoemulsions, with potential applications in the food industry

Effect of temperature and shear on the microstructure of a microbial polysaccharide secreted by Sphingomonas species in aqueous solution

Diutan gum is a biological polymer produced by Sphingomonas sp. In aqueous solution it shows gel-like structure under quiescent conditions. However, the flow-induced evolution of its viscoelastic properties and its microstructure are not known. In this work, the viscoelastic moduli were obtained under a flow field, applied in parallel, as a function of the temperature for 0.5 wt% diutan gum aqueous solutions. As both stress and temperature increase a decrease in the viscoelastic properties occurred, due to the fact that the molecular interactions decreased. Nevertheless, at stresses within the zero-shear viscosity region of the flow curves, no changes were observed. In addition, high stress values dampened the effect of the temperature. The results obtained are very interesting from an industrial application perspective.Ministerio de Economía y Competitividad CTQ2015-70700-

Processing and formulation optimization of mandarin essential oil-loaded emulsions developed by microfluidization

Emulsions can be used as delivery systems for bioactive ingredients for their incorporation in food products. Essential oils are natural compounds found in plants that present antioxidant and antimicrobial activity. Therefore, the main goal of this work was to develop emulsions, containing mandarin essential oil stabilized by two food-grade surfactants and guar gum, and to evaluate their physical stability. The initial droplet size of emulsions developed by microfluidization was optimized, obtaining diameters below one micron regardless of the processing conditions. However, the emulsion processed at 25,000 psi and one pass exhibited the lowest mean droplet sizes and polidispersity, and therefore, a higher stability. Different ratios of Tween 80 and Span 80 were assessed as stabilizers. Results obtained indicated that the ratio of surfactants had a significant effect on the mean droplet sizes, physical stability, and rheological properties. Thus, we found that the optimum ratio of surfactants was 75/25 (Tween80/Span80) on account of the lowest droplet mean diameters, lack of coalescence, and a low creaming rate. The rheological characterization of the stable emulsions showed a shear thinning flow behavior, and G" (loss modulus) values higher than G0 (storage modulus) values, in all the frequency range. The rheological behavior may be governed by the guar gum, which was confirmed by field emission scanning electron microscopy (FESEM). This research can be considered as the starting point for future applications of mandarin essential oil in emulsions, which can be incorporated in products as food preservatives.Ministerio de Economía y Competitividad CTQ2015-70700-

El acoso psicológico desde una perspectiva organizacional: papel del clima organizacional y los procesos de cambio

El estudio del acoso psicológico ha sido abordado desde diferentes enfoques y perspectivas, en los últimos años. Desde un enfoque organizacional el presente trabajo pretende analizar en qué medida el tipo de clima organizacional -apoyo, reglas, metas e innovación- y la presencia de procesos de cambio organizacional se relacionan con la incidencia de prácticas de acoso psicológico en el trabajo. En el estudio han participado 211 empleados/as de diferentes organizaciones de servicio, públicas y privadas. Los resultados han mostrado que la presencia de prácticas de acoso resulta contingente, tanto al tipo de clima que predomina en dicho entorno, como a los procesos de cambio organizacional que se dan en el mismo. Específicamente se ha encontrado que el clima de apoyo y el clima de reglas se relacionan con una menor presencia de las prácticas de acoso, mientras que el clima de metas y los procesos de cambio parece ser entornos más propicios para el desarrollo de las prácticas de acoso

La metodología Flipped Classroom en la enseñanza híbrida universitaria: la satisfacción de los estudiantes [Flipped Classroom Methodology for Hybrid Learning in the Higher Education Context: Students Satisfaction]

Tras más de dos décadas de desarrollo de la enseñanza online, hace su aparición la enseñanza híbrida que busca, entre otros objetivos, mejorar los puntos débiles de la docencia exclusivamente online. La enseñanza híbrida necesita dotarse de metodologías e instrumentos que desarrollen todo su potencial didáctico y es en este contexto en el que se inscribe el presente trabajo. Hemos investigado la satisfacción de los estudiantes con la enseñanza híbrida en relación a la exclusivamente online, así como la percepción de los mismos en cuanto a la aplicación de la metodología Flipped Classroom (FC) en el ámbito híbrido en oposición a la metodología tradicional de clases presenciales magistrales. La investigación se ha desarrollado para ciencias sociales, en aulas híbridas universitarias, aplicando métodos cualitativos y cuantitativos, como encuestas y reuniones semiestructuradas con los alumnos, durante el segundo semestre del curso 2016/17. Las conclusiones obtenidas son muy alentadoras, mostrando un alto grado de satisfacción por parte de los estudiantes con el entorno híbrido en comparación al exclusivamente online y con la aplicación de la metodología FC en dicho ámbito, frente a metodologías más tradicionales. [After more than two decades of the development of online education, the recent emergence of hybrid education has tried to overcome the weaknesses of the teaching exclusively online. The main goal of this paper is to identify the best methodologies and instruments of the hybrid education in order to develop all its educational potential. In this regard, we have addressed the satisfaction of the students with the hybrid teaching format compared to the exclusively online, as well as their perception with the new Flipped Classroom (FC) methodology as opposed to the traditional methodology in which theory is explained in class and practice is implemented at home. The research has been carried out in university hybrid courses in social sciences and has used qualitative and quantitative methods, such as surveys and structured interviews or appointments with students during the second semester of the 2016/17 academic year. So far, the conclusions of the research are very encouraging. In particular, they show a high degree of students’ satisfaction with the hybrid format compared to the exclusively 100% online and with the application of the FC methodology with respect to the traditional teaching methodology.

Influence of the Homogenization Pressure on the Rheology of Biopolymer-Stabilized Emulsions Formulated with Thyme Oil

Different continuous phases formulated with ecofriendly ingredients such as AMIDET®N, an ecological surfactant, as well as welan and rhamsan gums were developed. An experimental design strategy was been in order to study the influence of the ratio of these two polysaccharides and the homogenization pressure applied in a microfluidizer on the critical shear stress for the continuous phases developed. A pure rhamsan gum solution was selected as the starting point for further study based on the production of thyme oil-in-water emulsions. The effect of the homogenization pressure on the physical stability, critical shear stress and droplet size distribution was analyzed for emulsions with optimized values of the rhamsan–welan ratio. These bioactive thyme oil-in-water emulgels could be considered as delivery systems with potential applications in the food industry.Ministerio de Economía y Competitividad CTQ2015-70700-PEuropean Commission (FEDER Programme

Caracterització reològica d’una suspoemulsió comercial per a ús agroquímic

Se estudian las propiedades reológicas de una suspoemulsión comercial para uso agroquímico. Se comparan los resultados obtenidos mediante curvas de flujo y ensayos en cizalla oscilatoria de baja amplitud para cinco temperaturas distintas en el intervalo de 5 a 25ºC. Las curvas de flujo, ponen de manifiesto que la suspoemulsión se caracteriza por presentar un comportamiento pseudoplástico, menos acusado a medida que aumenta la temperatura, que se ajusta al modelo de Sisko. Barridos de esfuerzo realizados a 0,1Hz permiten determinar el reducido rango viscoelástico lineal de la suspoemulsión, que depende de la temperatura. Los espectros mecánicos, entre 3Hz y 0,01 Hz, revelan que el sistema manifiesta propiedades viscoelásticas con un comportamiento típico de gel débil. La aparición de un mínimo en el valor de G” respecto a la frecuencia ha permitido estimar el módulo plateau, el cual desciende con el aumento de temperatura según una ecuación tipo Arrhenius. Aún así, la suspoemulsión presenta un carácter elástico que favorece su estabilidad física con el tiempo de almacenamiento. Se ha demostrado además que el sistema no sigue la regla de Cox-Merz.This study deals with a rheological characterization of a commercial suspoemulsion used for agrochemical application. Steady state flow and low amplitude oscillatory shear (SAOS) behaviour at five different temperazatures in the range of 5 to 25 °C are compared. Flow curves revealed that the pseudoplastic behaviour obeying the Sisko model was less pronounced as temperature was increased. Stress sweeps performed at 0.1 Hz allowed to determine the small linear viscoelastic range of the suspoemulsion, which depended on the temperature. The suspoemulsion at the different temperatures studied exhibited the typical weak-gel viscoelastic behaviour under SAOS between 3 and 0.01 Hz. The occurrence of a minimum of G” allowed to calculate the “Plateau” modulus, which decreased with temperature according to an Arrhenius type equation. Despite of that, the suspoemulsion showed an elastic character, which favoured its physical stability. Also, It has been demonstrated that the system did not follow the Cox-Merz superposition rule.S’estudien les propietats reològiques d’una suspoemulsió comercial per a ús agroquímic. Es comparen els resultats obtinguts mitjançant corbes de flux i assajos en cisalla oscil•latòria de baixa amplitud per a cinc temperaturas diferents en l’interval de 5 a 25 ºC. Les corbes de flux, posen de manifest que la suspoemulsió es caracteritza per presentar un comportament pseudoplàstic, menys acusat a mesura que augmenta la temperatura, que s’ajusta al model de Sisko. Els escaneigs d’esforç realitzats a 0,1Hz permeten determinar el reduït rang viscoelàstic lineal de la suspoemulsió, que depèn de la temperatura. Els espectres mecànics, entre 3Hz i 0,01 Hz, revelen que el sistema manifesta propietats viscoelàstiques amb un comportament típic de gel feble. L’aparició d’un mínim en el valor de G” respecte a la freqüència ha permès estimar el mòdul plateau, el qual disminueix quan augmenta la temperatura segons una equació de tipus Arrhenius. Tot i això, la suspoemulsió presenta un caràcter elàstic que afavoreix la seva estabilitat física durant el temps d’emmagatzematge. S’ha demostrat a més que el sistema no segueix la regla de Cox-Merz.Ministerio de Ciencia e Innovación del Gobierno de EspañaBayer-Crop Scienc

Influence of primary homogenization step on microfluidized emulsions formulated with thyme oil and Appyclean 6548

This contribution deals with the development of emulsions formulated using thyme essential oil and a new biomass-derived surfactant. In addition, this work extends our knowledge concerning the factors that can influence stability and droplet size distributions of microfluidized emulsions, such as the geometry of the rotor–stator used and the homogenization rate in the primary homogenization. Stable thyme oil-in-water emulsions (30 wt%) containing submicron droplets were formed. Interestingly, laser diffraction results reveal that mean droplet sizes are mainly controlled by homogenization rates and polydispersity by the rotor–stator geometry used in the first step of homogenization. In addition, higher droplet sizes for pre-emulsions seem to be a key factor in order to reduce both the degree of recoalescence and the size of the droplets in the second homogenization step. Furthermore, higher droplet sizes in the pre-emulsion favour higher physical stability of the final emulsions. Finally, this research highlights the importance of controlling primary homogenization conditions for the physical stability of microfluidized emulsions that contain natural ingredients.Ministerio de Economía y Competitividad (Project CTQ2015-70700-P)European Commission (FEDER Programme

Utilización de antimicrobianos en los hospitales públicos de Andalucía: 1995-1996

Objetivo. Describir el consumo de antiinfecciosos en los hospitales públicos de Andalucía durante los años 1995 y 1996. Establecer las diferencias cuali y cuantitativas en el consumo, cuando se expresa en DDD o DDPs. Método. Se estudió el consumo de antimicrobianos mediante el cálculo de las DDDs y DDPs/100 estancias-día, siguiendo básicamente la clasificación ATC. Se analizó la utilización para el conjunto de los hospitales y por tipo de hospital (regional, de especialidades y comarcal), valorándose los grupos terapéuticos y antimicrobianos más utilizados mediante una clasificación descendente en consumo. Resultados. En ambos años participaron 27 de 31 hospitales (87,1%). El consumo total en DDD/100 Est.-día fue de 73,67 y 75,17 y en DDPs/100 Est.-día fue de 64,61 y 65,39. El 80% de la utilización se concentra en penicilinas, cefalosporinas, quinolonas y aminoglucósidos. Destaca un 24% de aumento interanual en las quinolonas. Amoxicilinaclavulánico es el antibiótico con una mayor utilización en los dos años: 9,84 y 11,93 DDDs/100 Est.-día. La diferencia en el consumo global resultó ser un 12,6% más baja si se expresa en DDP.Objetive. To describe the consumption of anti-infectious agents in public hospitals of Andalucia, Spain, in 1995 and 1996. To establish qualitative and quantitative differences in consumption expressed as DDD and PDD. Method. Antimicrobial consumption was calculated by DDD and PDD/100 hospital days following the ATC classification. An analysis was made of drug use by the overall group of hospitals and by the type of hospital (regional, specialty, and local). Therapeutic groups and the most frequently used antimicrobial agents were analyzed by a descending classification of consumption. Results. In the two years of the study, 27 of 31 (87.1%) hospitals participated. Overall consumption by DDD/100 hospital days was 73.67 and 75.17 and by PDD/100 hospital days, 64.61 and 65.39. Eighty percent of the drugs used were penicillins, cephalosporins, quinolones and aminoglycosides. An interannual increase of 24% in quinolone use was noteworthy. Amoxicillin-clavulanic acid was the antibiotic most often used in both years: 9.84 and 11.93 DDD/100 hospital days. The difference in overall consumption was 12.0%, with a lower PDD