Pablo Ramírez

Direct electron transfer from graphite and functionalized gold electrodes to T1 and T2/T3 copper centers of bilirubin oxidase.

Direct electron transfer (DET) from bare spectrographic graphite (SPGE) or 3-mercaptopropionic acid-modified gold (MPA-gold) electrodes to Trachyderma tsunodae bilirubin oxidase (BOD) was studied under anaerobic and aerobic conditions by cyclic voltammetry and chronoamperometry. On cyclic voltammograms nonturnover Faradaic signals with midpoint potentials of about 700 mV and 400 mV were clearly observed corresponding to redox transformations of the T1 site and the T2/T3 cluster of the enzyme, respectively. The immobilized BOD was differently oriented on the two electrodes and its catalysis of O(2)-electroreduction was also massively different. On SPGE, where most of the enzyme was oriented with the T1 copper site proximal to the carbon with a quite slow ET process, well-pronounced DET-bioelectroreduction of O(2) was observed, starting already at >700 mV vs. NHE. In contrast, on MPA-gold most of the enzyme was oriented with its T2/T3 copper cluster proximal to the metal. Indeed, there was little DET-based catalysis of O(2)-electroreduction, even though the ET between the MPA-gold and the T2/T3 copper cluster of BOD was similar to that observed for the T1 site at SPGE. When BOD actively catalyzes the O(2)-electroreduction, the redox potential of its T1 site is 690 mV vs. NHE and that of one of its T2/T3 copper centers is 390 mV vs. NHE. The redox potential of the T2/T3 copper cluster of a resting form of BOD is suggested to be about 360 mV vs. NHE. These values, combined with the observed biocatalytic behavior, strongly suggest an uphill intra-molecular electron transfer from the T1 site to the T2/T3 cluster during the catalytic turnover of the enzyme.

Formulation and optimization by experimental design of eco-friendly emulsions based on d-limonene.

d-Limonene is a natural occurring solvent that can replace more pollutant chemicals in agrochemical formulations. In the present work, a comprehensive study of the influence of dispersed phase mass fraction, ϕ, and of the surfactant/oil ratio, R, on the emulsion stability and droplet size distribution of d-limonene-in-water emulsions stabilized by a non-ionic triblock copolymer surfactant has been carried out. An experimental full factorial design 3(2) was conducted in order to optimize the emulsion formulation. The independent variables, ϕ and R were studied in the range 10-50 wt% and 0.02-0.1, respectively. The emulsions studied were mainly destabilized by both creaming and Ostwald ripening. Therefore, initial droplet size and an overall destabilization parameter, the so-called turbiscan stability index, were used as dependent variables. The optimal formulation, comprising minimum droplet size and maximum stability was achieved at ϕ=50 wt%; R=0.062. Furthermore, the surface response methodology allowed us to obtain the formulation yielding sub-micron emulsions by using a single step rotor/stator homogenizer process instead of most commonly used two-step emulsification methods. In addition, the optimal formulation was further improved against Ostwald ripening by adding silicone oil to the dispersed phase. The combination of these experimental findings allowed us to gain a deeper insight into the stability of these emulsions, which can be applied to the rational development of new formulations with potential application in agrochemical formulations.

Adsorption at the biocompatible α-pinene–water interface and emulsifying properties of two eco-friendly surfactants

In this contribution, we provide an accurate characterization at the α-pinene/water interface of two commercial polyoxytheylene glycerol ester surfactants which differ in the number of ethylene oxide (EO) groups, comprising a systematic analysis of interfacial pressure isotherms, dynamic curves, interfacial rheology and emulsifying properties. Polyoxyethylene glycerol esters derived from cocoa oil are non-ionic surfactants obtained from a renewable source which fulfill the environmental and toxicological requirements to be used as eco-friendly emulsifying agents. α-Pinene is a renewable biosolvent completely insoluble in water, which could find numerous applications. Interfacial rheology and equilibrium interfacial pressure data fitted a rigorous reorientation model that assumes that the surfactant molecules, when adsorbed at the interface, can acquire two orientations. The surfactant with the highest number of EO groups (Levenol C201) turned out to be more surface active at the α-pinene/water interface. In addition, the surfactant with the lowest number of EO groups (Levenol H&B) is solubilized into the adjacent oil phase. Slightly concentrated α-pinene emulsions were obtained using both surfactants. Nevertheless, more stable α-pinene emulsions with smaller droplet sizes and lower polidispersity were obtained when Levenol C201 was used as emulsifier instead of Levenol H&B. The systematic characterization presented in this work provides important new findings on the interfacial and emulsifying properties of polyoxytheylene glycerol ester surfactants, which can be applied in the rational development of new biocompatible products.

Interfacial characterization of Pluronic PE9400 at biocompatible (air-water and limonene-water) interfaces.

In this work, we provide an accurate characterization of non-ionic triblock copolymer Pluronic PE9400 at the air-water and limonene-water interfaces, comprising a systematic analysis of surface tension isotherms, dynamic curves, dilatational rheology and desorption profiles. The surface pressure isotherms display two different slopes of the Π-c plot suggesting the existence of two adsorption regimes for PE9400 at both interfaces. Application of a theoretical model, which assumes the coexistence of different adsorbed states characterized by their molar areas, allows quantification of the conformational changes occurring at the adsorbed layer, indentifying differences between the conformations adopted at the air-water and the limonene-water interface. The presence of two maxima in the dilatational modulus vs. interfacial pressure importantly corroborates this conformational change from a 2D flat conformation to 3D brush one. Moreover, the dilatational response provides mechanical diferences between the interfacial layers formed at the two interfaces analyzed. Dynamic surface pressure data were transformed into a dimensionless form and fitted to another model which considers the influence of the reorganization process on the adsorption dynamics. Finally, the desorption profiles reveal that Pluronic PE9400 is irreversibly adsorbed at both interfaces regardless of the interfacial conformation and nature of the interface. The systematic characterization presented in this work provides important new findings on the interfacial properties of pluronics which can be applied in the rational development of new products, such as biocompatible limonene-based emulsions and/or microemulsions.

Folding and Unfolding in the Blue Copper Protein Rusticyanin:Role of the Oxidation State

The unfolding process of the blue copper protein rusticyanin has been studied from the structural and the thermodynamic points of view at two pH values (pH 2.5 and 7.0). When Rc unfolds, copper ion remains bound to the polypeptide chain. Nuclear magnetic resonance data suggest that three of the copper ligands in the folded state are bound to the metal ion in the unfolded form, while the other native ligand is detached. These structural changes are reflected in the redox potentials of the protein in both folded and unfolded forms. The affinities of the copper ion in both redox states have been also determined at the two specified pH values. The results indicate that the presence of two histidine ligands in the folded protein can compensate the change in the net charge that the copper ion receives from their ligands, while, in the unfolded protein, charges of aminoacids are completely transferred to the copper ion, altering decisively the relative stability of its two-redox states.

Development of eco-friendly submicron emulsions stabilized by a bio-derived gum

Many traditional organic solvents are being gradually replaced by ecofriendly alternatives. D-Limonene is a terpenic (bio)-solvent that fulfils the requirements to be considered a green solvent. D-Limonene sub-micron emulsions suffer from Ostwald ripening destabilization. In this study, we examined the influence of the addition of a natural gum (rosin gum) to D-limonene in order to prevent Ostwald ripening. This contribution deals with the study of emulsions formulated with a mixture of D-limonene and rosin gum as dispersed phase and Pluronic PE9400 as emulsifier. The procedure followed for the development of these formulations was based on the application of product design principles. This led to the optimum ratio rosin gum/D-limonene and subsequently to the optimum surfactant concentration. The combination of different techniques (rheology, laser diffraction and multiple light scattering) was demonstrated to be a powerful tool to assist in the prediction of the emulsions destabilization process. Not only did the addition of rosin gum highly increase the stability of these emulsions by inhibiting the Ostwald ripening, but it also reduced the emulsions droplet size. Thus, we found that stable sub-micron D-limonene-in-water emulsions have been obtained in the range 3-6 wt% Pluronic PE-9400 by means of a single-step rotor/stator homogenizing process.

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.

Development of rosemary essential oil nanoemulsions using a wheat biomass-derived surfactant

In the present work aqueous-based emulsions formulated with bio-based solvents and surfactants were studied. The droplet size distribution, rheology and physical stability of rosemary essential oil/water emulsions formulated with an emulsifier derived from wheat waste (alkyl polypentoside) were investigated as a function of the dispersed phase concentration (10-50 wt%) by means of laser diffraction, multiple light scattering and rheology measurements. Subsequently, processing variables, such as the pressure and the number of microfluidization passes, were studied to the best formulation (20 wt% rosemary oil). The laser diffraction technique revealed that monodispersed submicron emulsions were obtained for oil phase concentrations below 20 wt%. All emulsions showed Newtonian behavior, except for the emulsion containing 50 wt% oil, which exhibited shear-thinning properties. Moreover, the main destabilization mechanism of all the emulsions was creaming. The combination of techniques used demonstrated that the emulsion containing 20 wt% rosemary essential oil (REO) and prepared by microfluidization at 2500 psi (17.2 MPa) exhibited the longest physical stability and the smallest droplet size after 3passes. This research is a contribution to sustainable development not only by using chemicals derived from renewable raw materials but also by achieving stable emulsions with a low surfactant/oil mass ratio.

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.