Nuria Calero

Influence of polysaccharides on the rheology and stabilization of α-pinene emulsions.

This work focuses on the need to include polysaccharides in a slightly concentrated O(α-pinene)/W emulsion, formulated with amphiphilic copolymers as emulsifiers. Rheology, laser diffraction and multiple light scattering were the main techniques used to assess the performance of gellan gum, xanthan gum and a mixture of both hydrocolloids as stabilizers. Small amplitude oscillatory shear results were consistent with the existence of three distinct microstructures and relaxation mechanisms, which depended on the hydrocolloid system used. The mechanical spectrum of the emulsion containing both polysaccharides signalled the occurrence of thermodynamic incompatibility between the two. Flow curves fitted to the Carreau-Yasuda model demonstrated a negative synergistic effect between gellan and xanthan gums. The droplet size distribution was similar for these systems, which highlighted the importance of the continuous phase for emulsion stability. Multiple light scattering illustrated that creaming was practically eliminated by the incorporation of polysaccharides, coalescence being the main destabilization mechanism.

Optimization of a green emulsion stability by tuning homogenization rate

Green chemistry increases the design of new products and processes that consider the reduction or removal of the use or production of hazardous substances. This study is focused on the development of stable emulsions using ecofriendly ingredients, taking into account that energy requirements should be minimized. The physical stability of the emulsions studied was explored by means of a combination of different techniques, such as laser diffraction, multiple light scattering and rheology. The coalescence process was detected, not only by laser diffraction measurements, but also by the analysis of the plateau modulus with aging time. This rheological parameter was also useful to distinguish between grades of flocculation. In addition, the Turbiscan stability index showed that the stability was enhanced at higher homogenization rates for 30 wt% emulsions, and the opposite was true for 40 wt% emulsions. The results obtained from the combination of different techniques demonstrated that the most stable emulsion was achieved with the 40 wt% dispersed phase, using less energy input, which lies at the heart of a sustainable society.

Assessing differences between Ostwald ripening and coalescence by rheology, laser diffraction and multiple light scattering

This contribution deals with the study of the influence of surfactant ratio, namely triblock copolymer (Pluronic PE9400) to polyoxyethylene glycerol fatty acid ester (Levenol C201), on the stability of emulsions formulated with a mixture of two biosolvents (N,N Dimethyl Decanamide and D-limonene), which find applications as carriers of agrochemicals. Emulsions containing Pluronic, regardless of the concentration studied, underwent Ostwald ripening while coalescence controlled the destabilization process of emulsions containing Levenol C201 as the only emulsifier. The physical stability of the emulsions was analysed not only by means of mean diameters determined by laser diffraction but also with respect to their rheological properties and the so-called TSI parameter derived from multiple light scattering measurements with aging time. We propose that the different structures of both surfactants at the oil/water interface may be responsible for the occurrence of different destabilization mechanisms. It is likely that Copolymer Pluronic PE9400 formed multilayers in the emulsions studied, which may promote flocculation during processing and, subsequently, Ostwald ripening. In contrast, Levenol C201 probably formed a compact adsorbed layer with the molecules perpendicularly oriented to the interface. This work illustrates to what extent the combination of information provided by Multiple Light Scattering, rheology and laser diffraction enables the detection and monitoring of destabilization mechanisms such as Ostwald ripening and coalescence. In addition, this research highlights the importance of surfactant selection for the physical stability of emulsions that exhibited similar droplet size distributions just after preparation.

Non-Linear Dynamic Viscoelasticity of Xanthan Gum Solutions

Xanthan gum is a high molecular-weight polysaccharide, soluble in cold water, and mainly used in the food industry as a thickener and stabiliser. The rheological properties of xanthan gum are therefore of key interest to improve their thickening and stabilising properties. Recently, large amplitude oscillatory shear (LAOS) measurements have been carried out in order to gain a deeper insight into microstructural changes in complex fluids such as xanthan gum solutions. This work has studied the influence of salt concentration on the rheological properties of xanthan gum solutions, comparing the results obtained by means of traditional small amplitude oscillatory shear (SAOS) and LAOS measurements.

Caracterización reológica de una suspoemulsión comercial para uso agroquímico

Se estudian las propiedades reologicas de una suspoemulsion comercial para uso agroquimico. 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 suspoemulsion se caracteriza por presentar un comportamiento pseudoplastico, 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 viscoelastico lineal de la suspoemulsion, que depende de la temperatura. Los espectros mecanicos, entre 3Hzy 0,01 Hz, revelan que el sistema manifiesta propiedades viscoelasticas con un comportamiento tipico de gel debil. La aparicion de un minimo en el valor de G” respecto a la frecuencia ha permitido estimar el modulo plateau, el cual desciende con el aumento de temperatura segun una ecuacion tipo Arrhenius. Aun asi, la suspoemulsion presenta un caracter elastico que favorece su estabilidad fisica con el tiempo de almacenamiento. Se ha demostrado ademas que el sistema no sigue la regla de Cox-Merz.

Development of food emulsions containing an advanced performance xanthan gum by microfluidization technique

Gums are often used to increase the viscosity of the continuous phase of oil-in-water emulsions in order to reduce or inhibit some destabilization processes such as creaming. A new type of xanthan gum, advanced performance xanthan gum, which possesses improved rheological properties, has been used as a stabilizer. The addition of advanced performance xanthan gum to egg protein-based emulsions prepared at different homogenization pressures in Microfluidizer was studied. These emulsions showed different droplet size distributions and flocculation degrees. However, all the emulsions studied exhibited the same viscoelastic properties, characterized by a crossover point in the mechanical spectra. This work demonstrates the essential role of this novel gum in the rheology of emulsions. In addition, there is a direct relation between homogenization pressure and flocculation degree. This flocculation led to destabilization by coalescence in these emulsions, being the emulsion processed at the smallest homogenization pressure the most stable.

Time-dependent behavior in analyte-, temperature-, and shear-sensitive Pluronic PE9400/water systems

AbstractPluronic PE9400/water binary systems at different concentrations were characterized by means of rheological and microstructural techniques. Temperature ramps revealed a structural transition defined by three zones, which determine time-dependent behaviors. Thus, non-time-dependent, antithixotropic, and thixotropic behaviors were observed depending on Pluronic’s concentration and temperature. These phenomena were analyzed resorting to rheological tools, namely hysteresis loops and transient tests, and supported by Cryo-SEM. The results obtained demonstrated the shear-sensitive character of these systems. All properties presented by these systems make them adequate and interesting for many applications such as injectable systems for tissue repair. Graphical abstractInfluence of temperature on viscoelastic functions and microstructure for 25 wt% Pluronic PE9400/water system

Reología aplicada & tecnología de coloides. Aplicaciones en ingeniería de productos

espanolEn esta revision se recoge una descripcion detallada de la deuteracion de moleculas organicas utilizando la mezcla Cp2TiCl/Mn/D2O. Se trata de una deuteracion eficiente, selectiva, economica y respetuosa con el medio ambiente, la cual puede ser encuadrada dentro del concepto de Quimica Verde EnglishIn this review a detailed description of deuteration of organic molecules using Cp2TiCl/Mn/D2O mixture is reported. It is an efficient, selective and economic deuteration, respectful with the environment, which can be framed within the concept of Green Chemistry.espanolEn este documento se describen las diferentes lineas de investigacion en las que actualmente trabaja el grupo TIC 150: Tecnologia Electronica e Informatica Industrial del Departamento de Tecnologia Electronica (DTE) de la Universidad de Sevilla. Este grupo cuenta con una dilatada experiencia en proyectos de investigacion, tanto de convocatorias competitivas publicas, como en proyectos de investigacion en colaboracion con empresas. El TIC150 destaca por su elevada trasferencia tecnologica, asi como por su produccion cientifica. En este sentido, y a modo de ejemplo, en este trabajo se describen brevemente dentro de cada linea algunos de los proyectos mas representativos que reflejan el trabajo realizado. Asi pues, se hara especial hincapie en el proyecto SIIAM, proyecto del plan estatal actualmente activo, ya que auna las distintas lineas de investigacion del grupo de investigacion y, por tanto, supone un buen ejemplo de aplicacion EnglishThis document describes the different lines in which currently works the TIC150 research group: Electronic Technology and Industrial Computer Science, joined to the Department of Electronics Technology (DTE) of the University of Seville. This group has extensive experience in research projects, both competitive public calls and collaborative research projects with companies. The TIC150 stands out for its high technology transfer, as well as its scientific production. In this sense, as an example, this paper briefly describes some of the most representative projects (of different lines) which reflect the performed work. Thus, it will place special emphasis on the SIIAM project (funding through a governmental call). It is currently active and combines several lines research of the group, being a great example of application.En el Master Universitario en Diseno y Desarrollo de Productos e Instalaciones Industriales de la Escuela Politecnica Superior de la Universidad de Sevilla presentamos una serie de propuestas para desarrollar como proyectos de investigacion en la Asignatura Diseno y Fabricacion Asistidas por Ordenador (Bloque de Intensificacion I) y en el Trabajo Fin de Master, tecnicas de visualizacion con modelos de iluminacion global combinado con tecnicas de investigacion en aplicaciones informaticas orientadas al diseno. Estos trabajos han dado lugar a innovar desde el punto de vista docente incorporando nuevas tecnicas y metodos en asignaturas como por ejemplo, Representacion Fotorrealista y Animacion de Productos por Ordenador. En esta comunicacion presentaremos una serie de tecnicas que llevamos desarrollando desde el modelado tridimensional del producto hasta la obtencion de imagenes de sintesis digital, permitiendonos obtener una imagen de sintesis digital no solo del producto original, sino poder cambiar distintas formas y apariencias del mismo asi como su integracion en distintos entornos de uso o de operacion, incluso antes de su posible fabricacion.Ministerio de Industria, Energia y Comercio (Espana) y FEDER (European Union) Evaluacion de la homogenizacion por microcanales para la preparacion y caracterizacion de emulsiones submicronicas de aceites esenciales CTQ2015-70700-PespanolSe centra el trabajo en el estudio higienico, valorando y mensurando la existencia de riesgo y el nivel de exposicion a ruido por los profesionales de orquesta mediante estudio de caso con mediciones higienicas de ruido en la Real Orquesta Sinfonica de Sevilla (ROSS) en La opera Tosca de Puccini y el cuarto movimiento de la Novena Sinfonia de Beethoven. El conocimiento de las condiciones de trabajo desde la prevencion de riesgos laborales es un conocimiento evaluador para poder intervenir y esta ha sido la pauta a seguir. EnglishThe work focuses on hygienic study, valuing and measurand the existence of risk and the noise level exposured to noise by professionals of Orchestra through case study with hygienic measurements of noise in the Real Orquesta Sinfonica de Sevilla (ROSS) in the opera Tosca of Puccini and the fourth movement of Beethovens Ninth Symphony. The knowledge of conditions of work from the prevention of occupational risks is an evaluator knowledge to be able to intervene and this has been the pattern to follow.espanolEn este trabajo se muestra la viabilidad de utilizar tecnicas de analisis de series temporales para el problema de estimacion de la demanda. Los trabajos realizados incluyen aspectos iniciales de preparacion de datos, eleccion de las herramientas de procesado y analisis mediante tecnicas de series temporales. Quedan pendientes de desarrollo futuro la aplicacion de tecnicas de mineria de datos y su comparacion con los resultados de esta primera fase. EnglishIn this paper the feasibility of using techniques of time series analysis to the problem of estimating demand is shown. Works carried out include aspects of initial data preparation, choice of processing tools and analysis using time-series techniques. Application of data mining techniques and comparison with the results of this first phase are possible future works.espanolHoy en dia el interes por desarrollar nuevos materiales que satisfagan las necesidades tecnologicas, conlleva a un estudio continuo en la innovacion de los procesos de fabricacion. La ventaja que ofrecen las tecnicas pulvimetalurgicas de procesado en caliente convencional (HP) y directa (dHP), suponen un ahorro en tiempo que puede favorecer la viabilidad de nuevos materiales fabricados por estas tecnicas El potencial que presentan en cuanto a sus propiedades los materiales compuestos de matriz de titanio (TMCs), es muy valorado por el sector aeroespacial. La gran limitacion de uso de estos materiales en su aplicacion en otros sectores se debe en gran medida al alto coste. La linea de investigacion creada por este grupo en colaboracion con la empresa austriaca RHP-Technology, promueve el estudio-fabricacion-caracterizacion de TMCs fabricados mediante tecnicas pulvimetalurgicas avanzadas de compactacion en caliente. Esta colaboracion ofrece la posibilidad de producir materiales a la carta desde un punto de vista pulvimetalurgico. Los materiales estudiados principalmente son materiales compuestos de matriz titanio (TMCs) reforzados con particulas ceramicas como son el boro amorfo (B), el carburo de boro (B4C) y el diboruro de titanio (TiB2), con el objetivo de promover reacciones entre la matriz de titanio y las particulas de ceramicos que consoliden nuevos compuestos que actuan reforzando la matriz in situ. EnglishNowadays, the interest in developing novel materials to achieve the technological needs, leads to an ongoing study on innovation of manufacturing processes. The advantages of conventional Hot Pressing technique (HP) and direct Hot Pressing (dHP) involve savings in time in order to promote the viability of new materials manufactured by hot consolidation processes. Titanium Metal matrix Composites (TMCs) offer interesting properties, which are highly valued by the aerospace sector. However, there are some use limitations of these materials in other sectors due to their high cost. The research created by this group in collaboration with the Austrian research-company RHP-Technology, promotes the study-manufacturing-characterization of these TMCs. This collaboration provides the possibility of manufacturing materials “a la carte” from a point of view of Powder Metallurgy (PM). The materials studied are primarily TMCs reinforced with ceramic particles as boron amorphous (B), boron carbide (B4C) and titanium diboride (TiB2). By the addition of these ceramic materials to the matrix, in situ reactions between the matrix and the ceramic reinforcement are expected. In this respect, the titanium matrix becomes reinforced.espanolLos contaminantes organicos perfluorados, presentes en numerosos objetos de nuestra vida cotidiana, forman parte de los llamados contaminantes emergentes, que empiezan a ser regulados por ley y cuyos efectos sobre los organismos y el medio ambiente aun no estan bien evaluados. Estos compuestos se aplican en muchos productos industriales y domesticos por su resistencia al calor y su capacidad de repeler el agua y el aceite. La leche materna se ha utilizado como marcador biologico de la contaminacion ambiental ya que, por los procesos de bioacumulacion en tejido graso, muchos compuestos quimicos alcanzan concentraciones facilmente medibles en esta matriz. Dada la complejidad de la misma, y las dificultades que ofrece para su estudio desde un punto de vista analitico, este trabajo se ha centrado en la optimizacion y validacion de una nueva y sencilla metodologia analitica para la determinacion de cinco compuestos perfluorados (cuatro acidos perfluoroalquilicos (de C5 a C8) y el sulfonato de perfluorooctano) en leche materna mediante extraccion por sorcion sobre barras agitadoras, previa precipitacion quimica de grasas y proteinas, y posterior analisis mediante cromatografia de liquidos de ultra-resolucion acoplada a espectrometria de masas en tandem. EnglishPerfluoroalkyl compounds, present in several products of our everyday life, are part of the so-called emerging contaminants. Although they are starting to be regulated, their effects over organisms and the environment have not been well evaluated yet. Their widespread use on industrial and domestic products is due to their thermal stability and their unique ability to repel both water and oil. Breast milk has been used as biomarker of environmental pollution because several chemical compounds are bioaccumulated at quantifiable concentration levels in this fatty tissue. Due to the analytical challenge that involves this complex matrix, this work has been focused on the optimization and validation of a novel and simply analytical methodology for the determination of five perfluoroalkyl compounds (four perfluoroalkyl carboxylic acids (from C5 to C8) and perfluorooctane sulfonate) in breast milk. The analytical method involves a stir-bar sorptive extraction and analysis by UHPLC-MS/MS.