Effect of fatty acids on self-assembly of soybean lecithin systems

With the increasing interest in natural formulations for drug administration and functional foods, it is desirable a good knowledge of the phase behavior of lecithin/fatty acid formulations. Phase structure and properties of ternary lecithin/fatty acids/water systems are studied at 37. °C, making emphasis in regions with relatively low water and fatty acid content. The effect of fatty acid saturation degree on the phase microstructure is studied by comparing a fully saturated (palmitic acid, C16:0), monounsaturated (oleic acid, C18:1), and diunsaturated (linoleic acid, C18:2) fatty acids. Phase determinations are based on a combination of polarized light microscopy and small-angle X-ray scattering measurements. Interestingly, unsaturated (oleic acid and linoleic acid) fatty acid destabilizes the lamellar bilayer. Slight differences are observed between the phase diagrams produced by the unsaturated ones: small lamellar, medium cubic and large hexagonal regions. A narrow isotropic fluid region also appears on the lecithin-fatty acid axis, up to 8. wt% water. In contrast, a marked difference in phase microsctructure was observed between unsaturated and saturated systems in which the cubic and isotropic fluid phases are not formed. These differences are, probably, a consequence of the high Krafft point of the C16 saturated chains that imply rather rigid chains. However, unsaturated fatty acids result in more flexible tails. The frequent presence of, at least, one unsaturated chain in phospholipids makes it very likely a better mixing situation than in the case of more rigid chains. This swelling potential favors the formation of reverse hexagonal, cubic, and micellar phases. Both unsaturated fatty acid systems evolve by aging, with a reduction of the extension of reverse hexagonal phase and migration of the cubic phase to lower fatty acid and water contents. The kinetic stability of the systems seems to be controlled by the unsaturation of fatty acids.Dr. C.A. Godoy is grateful for her scholarship to the Agencia Española de Cooperación Internacional para el Desarrollo (AECID), Universidad de Alcalá and Banco Santander, through the “Becas Miguel de Cervantes Saavedra” Program, and to the Universidad del Valle for the bibliographic resources provided. Jaume Caelles from the SAXS-WAXS service at IQAC is gratefully for performing the measurements. Imma Carrera is acknowledged for sample preparation. Ignacio Jiménez is grateful for helping in graph improvement.Peer reviewe

Liminalidad, sensibilidad y simetríaen la investigación : difracciones metodológicas en el estudio de la muerte encefálica

This paper presents a methodological diffraction on our research about brain death. We focus on describing those encounters between researchers and participants that are usually summarized as entrance to the field and consider them liminal moments. Drawing on the tensions and uncertainties, we suggest that these liminal moments, rather than constituting mere formalities, are accounting for our object of study. On the one hand, we argue that our research practices are involved in enacting such object. On the other hand, we perform a symmetrical turn to the ways in which sensitive topics are investigated and displace the notion of sensitivity from its enunciation as a property of given topics to conceiving it as a research practice. Finally, we argue for the need to approach liminal moments in research with a sensitivity capable of accounting for dissonance, interference and tension.En este artículo hacemos una difracción metodológica sobre nuestra investigación acerca de la muerte encefálica. Nos centramos en la descripción de los encuentros entre investigadoras y participantes, que solemos resumir como la entrada al campo, y los consideramos momentos liminales. A partir de la narración de las tensiones y las incertidumbres, planteamos que estos momentos liminales, lejos de constituir meros trámites, ya dan cuenta de nuestro objeto de estudio. Así, por un lado, planteamos que nuestras prácticas de investigación participan del enactment del objeto. Por otro lado, hacemos un giro simétrico a la propuesta de los temas sensibles y desplazamos la noción de sensibilidad desde su enunciación como propiedad de ciertos temas hacia su ejercicio como práctica en la investigación. Finalmente, defendemos la necesidad de aproximarnos a estos momentos liminales con una sensibilidad que sea capaz de recoger la disonancia, las interferencias y las tensiones

Structure and phase equilibria of the soybean lecithin/PEG 40 monostearate/water system

PEG stearates are extensively used as emulsifiers in many lipid-based formulations. However, the scheme of the principles of the lipid-surfactant polymer interactions are still poorly understood and need more studies. A new phase diagram of a lecithin/PEG 40 monostearate/water system at 30 C is reported. First, we have characterized the binary PEG 40 monostearate/water system by the determination of the critical micelle concentration value and the viscous properties. Then, the ternary phase behavior and the influence of phase structure on their macroscopic properties are studied by a combination of different techniques, namely, optical microscopy, small-angle X-ray scattering, differential scanning calorimetry, and rheology. The phase behavior is complex, and some samples evolve even at long times. The single monophasic regions correspond to micellar, swollen lamellar, and lamellar gel phases. The existence of extended areas of phase coexistence (hexagonal, cubic, and lamellar liquid crystalline phases) may be a consequence of the low miscibility of S40P in the lecithin bilayer as well as of the segregation of the phospholipid polydisperse hydrophobic chains. The presence of the PEG 40 monostearate has less effect in the transformation to the cubic phase for lecithin than that found in other systems with simple glycerol-based lipids.The authors are grateful to Professor Michael Gradzielski for contacting Evonic Goldschmidt GmbH, who supplied us the TEGO® Acid S40P reagent. Marta Rodriguez is gratefully acknowledged for preparing the samples for SAXS analysis and Jaume Caelles from the SAXSWAXS service at IQAC for performing the measurements. Professor Pilar Tarazona is gratefully acknowledged for allowing the use of DSC equipment and Dr. Natali Fernandez for training in that technique. G. Zhang grateful for the Erasmus mobility grant, and M. Díaz grateful for her scholarship to the Agencia Española de Cooperación Internacional para el Desarrollo (AECID), Universidad de Alcalá and Banco Santander, through the “Becas Miguel de Cervantes Saavedra” Program. This paper is dedicated to the memory of our dear Prof. Ali Khan, who was a master in phase behavior.Peer reviewe

Reseña del blog IC-Investigación Cualitativa

El blog IC-Investigación Cualitativa és una eina interessant per a les persones que realitzem recerca social, ja que ofereix un recull parcial dels recursos, sobre metodologia qualitativa, disponibles a la xarxa i els exposa organitzats temàticament. Així, hi podem trobar articles, capítols, llibres, pàgines d'autora, vincles a revistes, grups de recerca, congressos, programes informàtics o altres portals web. No es tracta d'una centralització de materials, sinó de l'enxarxament de diferents recursos ja existents, ja que es mantenen els links a les pàgines on es localitzen. Això permet una doble tasca, difondre els propis materials i visibilitzar les fonts i recursos que els han fet disponibles.The blog IC-Investigación Cualitativa is an interesting tool for those whose realize social investigation since it offers a summary of resources, on qualitative methodology, available in the network and exhibits them thematicly. This way, we can find articles, chapters, books, authoress's pages, links to magazines, groups of investigation, congresses, IT programs or other web portals.It is not a question of material's centralization, but of an interconnection of different already existing resources, since there are kept the links of the pages in which they are located. This allows a double task, to spread the materials and to make visible the sources and resources that have made them available.El blog IC-Investigación Cualitativa es una herramienta interesante para las personas que realizamos investigación social ya que ofrece una recopilación de recursos, sobre metodología cualitativa, disponibles en la red y los expone temáticamente. Así, podemos encontrar artículos, capítulos, libros, páginas de autora, vinculos a revistas, grupos de investigación, congresos, programas informáticos u otros portales web.No se trata de una centralización de materiales, sino de un enlazamiento de diferentes recursos ya existentes, ya que se mantienen los vínculos de las páginas en las cuales se localizan. Esto permite una doble tarea, difundir los propios materiales y visibilizar las fuentes y recursos que los han hecho disponibles

De la prevención a la anticipación en biomedicina : la transferencia de órganos y tejidos

Actualmente en las sociedades occidentales, podemos observar nuevas prácticas que son a la vez realidad y ficción en tanto se desarrollan en el terreno de lo posible, lo imaginable y lo óptimo. En el presente artículo, nos centramos en el caso de la transferencia de órganos y tejidos para describir cómo las actantes y prácticas biomédicas implicadas se articulan configurándola como un proceso anticipatorio, es decir, como constante movimiento que aspira a traer futuros móviles al presente. A partir de un estudio de tipo etnográfico en el que exploramos el quehacer cotidiano de un equipo de coordinación de trasplantes Español, empezamos sugiriendo que el acto de donar se inserta como un imperativo más en la cada vez más individualizada gestión de los devenires biológicos de las ciudadanas. En segundo lugar, nos centramos en cómo la articulación del diagnóstico de muerte encefálica funciona en tanto entidad generadora de coherencia entre las diferentes temporalidades que se producen en la transferencia de órganos y tejidos. A continuación, exponemos los mecanismos de optimización que operan en las listas de espera materializando futuros imaginados. Finalmente, con la descripción de la latencia permanente en la que trabajan los equipos de coordinación de trasplantes, damos cuenta de cómo la biomedicina está pasando de generar prácticas insertadas en las lógicas de la prevención a prácticas que obedecen lógicas de preparaciónCurrently, within Western societies, we can see new practices that are at once reality and fiction as they unfold in the terrain of the possible, the imaginable and the optimum. In the present paper, we focus on the case of organ and tissues transfer to describe how those biomedical actants and practices involved are articulated, configuring it as an anticipatory process, namely as a constant movement attempting to bring mobile futures to the present. Drawing on an ethnographic study exploring the everyday activity of a Spanish transplant coordination team,, we begin by suggesting that donation gets inserted as an imperative in the increasingly individualized management of the citizens' biological becomings. Secondly, we turn to how the articulation of the brain death diagnosis functions as an entity capable of creating coherence between the different temporalities produced in the organs and tissues transfer. Then, we show the optimization mechanisms that operate within the waiting lists materializing imagined futures. Finally, by way of describing the permanent latency in which the transplant coordination teams work, we give an account of how biomedicine is turning away from generating practices inserted in a logic of prevention to practices that obey a logic of preparatio

Entrevista semiestructurada para la exploración de la violencia sexual sobre las mujeres en la relación de la pareja (EVS)

La violencia sexual en el ámbito de la relación de pareja es un problema grave experimentado por un alto número de mujeres. Sin embargo, es difícil su detección por la ausencia de reconocimiento social. Este tipo de violencia con frecuencia se da ligado a otras formas de maltrato, no obstante observamos que diferentes protocolos de entrevista publicados para explorarla, no la evalúan o lo hacen de forma superficial. Esto se suma al hecho de que algunas de las mujeres que lo sufren no son conscientes del maltrato, ni de la gravedad e impacto real que tiene sobre ellas. Por todo ello, nuestro objetivo es proponer una herramienta de recogida de información sobre la violencia sexual en la pareja, que facilite a las y los profesionales la detección de esta forma de violencia. Para ello, nos hemos basado en una revisión exhaustiva de la literatura científica y profesional y en nuestra propia experiencia. Como resultado presentamos la Entrevista Semiestructurada para la Exploración de la Violencia Sexual sobre las Mujeres en la Relación de Pareja (EVS), esperando que sea de utilidad a las y los profesionales que intervienen con mujeres que son víctimas de malos tratos.Sexual violence in intimate partner context is a serious problem that is experienced by a large number of women. However, its detection is difficult because the absence of social recognition. This kind of violence occurs frequently linked to other abuse types, however we realize that various interview protocols that have been published to explore it, don’t examine it or examine it superficially. In addition, some of women who are abused are not aware of this, neither its gravity nor real impact on themselves. Therefore, our purpose is to create a tool for collecting on information about intimate partner sexual violence and to help professionals in detecting this kind of violence. So, we have relied on a comprehensive review of the scientific and professional literature and our own experience. As a result we present the Entrevista Semiestructurada para la Exploración de la Violencia Sexual sobre las Mujeres en la Relación de Pareja (EVS), we hope to be useful for professionals who work with women who are victims of this abuse