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An investigation of various eddy viscosity models for accurate scale-resolving simulation of aerodynamics and aeroacoustics of a turbulent jet is presented. The models are considered from the perspective of solving the so-called gray area problem. This problem is related to nonphysical delay in the transition from Reynolds-averaged Navier–Stokes (RANS) to large-eddy simulation (LES) in hybrid RANS–LES approaches such as detached eddy simulation (DES) when applied to shear-layer flows. The performance of recently developed dynamic adapting subgrid length scales ([Formula: see text], [Formula: see text], and [Formula: see text]) and subgrid LES models ([Formula: see text] and S3QR) separately and together is demonstrated. The object of the investigation is an immersed subsonic turbulent jet. The simulations are carried out on a set of refining meshes using two different scale-resolving numerical algorithms with basic and higher-accuracy schemes on unstructured meshes. The evaluation of various eddy-viscosity models within the DES approach is mostly focused on the analysis of far-field noise. The study has clearly demonstrated the importance of both a numerical scheme and a subgrid turbulence model. The results show that some of the considered techniques provide the necessary accuracy to predict the noise generated by a turbulent jet. The features of the considered approaches are identified and discussed. Recommendations are formulated for the choice of the LES model and subgrid length scale for this kind of problem. The work of Jesús Ruano, F. Xavier Trias, and Joaquim Rigola has been financially supported by the project RETOtwin (PDC2021- 120970-I00) funded by MCIN/AEI/10.13039/501100011033 and European Union Next Generation European Union / Plan de Recuperación, Transformación y Resiliencia (EU/PRTR). The work of Alexey P. Duben and Andrey V. Gorobets was carried out within the state assignment of Ministry of Science and Higher Education of the Russian Federation (Theme No. 122041100137-4). NOISEtte computations were carried out using the equipment of the shared research facilities of high performance computing (HPC) computing resources at Lomonosov Moscow State University, the computing resources of the federal collective usage center Complex for Simulation and Data Processing for Mega-science Facilities at National Research Centre (NRC) “Kurchatov Institute” (http://ckp.nrcki.ru/), and the hybrid supercomputer K60 installed in the Supercomputer Centre of Collective Usage of Keldysh Institute of Applied Mathematics of Russian Academy of Sciences (KIAM RAS). The authors thankfully acknowledge these institutions.

Altres ajuts: acords transformatius de la UAB We study antiplane shear deformations for isotropic and homogeneous strain gradient mixtures of the Kelvin-Voigt type in a cylinder. Our aim is to analyze the behaviour of the solutions with respect to the time variable when a dissipative structural mechanism is considered. We study three different cases, each at a time. For each case we prove existence and uniqueness of solutions. We obtain the exponential decay of the solutions in the hyperviscosity and viscosity cases. Exponential decay is also expected when the dissipation is generated by the relative velocity (in the generic case, although a particular combination of the constitutive parameters leads to slow decay). These results are proved with the help of the theory of semigroups.

La disfàgia orofaríngia (DO) és un trastorn de la motilitat caracteritzat per la dificultat per formar o moure el bol de la boca a l'esòfag. Els espessidors, són una estratègia utilitzada per la DO, augmentant la viscositat del fluid. La viscositat, és un paràmetre reològic i es pot avaluar quantitativament. L'efecte terapèutic (ET) dels espessidors, es pot analitzar mitjançant estudis clínics (EC) i es poden establir nivells òptims de viscositat. Tanmateix, els espessidors, es comercialitzen descrivint la viscositat mitjançant descriptors qualitatius i recomanant intervals de viscositat arbitraris. La viscositat, es pot veure afectada durant la deglució per dos factors reològics: l'amilasa salival i la velocitat de cisalla. Tots dos factors, poden disminuir la viscositat i per tant, l'ET dels espessidors. Pocs estudis han examinat altres factors reològics diferents de la viscositat. En conseqüència, aquesta tesi, té els següents objectius: 1)Descriure l'efecte sobre la seguretat de la deglució de dos espessidors: un de goma xantana (XG) i un de barreja, a diversos nivells de viscositat; 2)Determinar el rang terapèutic i les dosis de viscositat òptimes per a cada fenotip de DO; 3)Descriure l'efecte de la viscositat de cisalla sobre l'eficàcia de deglució; 4)Descriure els factors reològics implicats en l'ET dels espessidors i determinar si aquesta informació s'inclou a l'etiquetat. Avaluar els riscos de l'ús de descriptors qualitatius; 5)Validar en diversos laboratoris internacionals un protocol científic per mesurar la viscositat i els factors reològics de deglució que l'afecten; 6)Avaluar la viscositat de cisalla, deformació extensional, força màxima, adhesivitat i cohesió per a dosis variables d'espessidors i determinar la seva relació amb la seguretat de la deglució avaluada per videofluoroscòpia. Aquest projecte de recerca inclou 4 capítols amb la següent metodologia i resultats: Capítol 1 - Tres EC amb dades de 327 pacients on s'analitza l'ET de 3 espessidors per a diversos nivells de viscositat (100-2000 mPa·s). Els resultats van mostrar, que l'ET presentava un comportament dependent de la viscositat, i que només es necessitaven dos nivells per cobrir més del 90% de la població. El residu oral augmenta amb l'augment de la viscositat; Capítol 2: l'anàlisi de 10 espessidors va mostrar que els fabricants recomanen l'ús de 3 nivells de viscositat seleccionats aleatòriament. No es va identificar cap descripció sobre l'efecte de l'amilasa o la velocitat de cisalla; Capítol 3: disseny i validació d'un protocol científic per mesurar la viscositat dels espessidors en 4 laboratoris internacionals, incloent la simulació de factors de deglució amb una variabilitat entre laboratoris inferior al 10%; Capítol 4: anàlisi de 4 propietats reològiques per a diferents dosis i la seva relació amb l'ET sobre la seguretat de la deglució, avaluada en 267 pacients. Els resultats van confirmar que la viscositat de cisalla és el principal paràmetre associat a la seguretat de la deglució. Les principals conclusions són: 1)Els espessidors, milloren la seguretat de la deglució mitjançant l'augment de la viscositat de cisalla d'una manera dosi-depenent. 2)Es pot establir un rang terapèutic entre 100 i 1000 mPa·s per a tractar pacients amb DO. L'augment de la viscositat per sobre de 800-1000 mPa·s no provoca cap millora significativa en la seguretat de la deglució; 3)L'augment de la viscositat de cisalla, està relacionat amb un augment del residu oral. 4)L'ús de descriptors qualitatius de viscositat en l'etiquetat dels espessidors comporta diversos riscos i contradiccions, que posen en perill la seguretat dels pacients; 5)Es pot aplicar a tot el món, un protocol reològic per mesurar la viscositat de cisalla en condicions experimentals que reprodueixen el comportament dels espessidors durant la deglució; 6)La viscositat de cisalla és la principal variable causant l'ET dels espessidors amb un fort efecte dosi-resposta. La disfagia orofaríngea (DO) es un trastorno de la motilidad caracterizado por la dificultad para formar o mover el cuenco de la boca en el esófago. Los espesantes, son una estrategia utilizada por la DO, aumentando la viscosidad del fluido. La viscosidad es un parámetro reológico y se puede evaluar cuantitativamente. El efecto terapéutico (ET) de los espesantes, se puede analizar mediante estudios clínicos (EC) y se pueden establecer niveles óptimos de viscosidad. Sin embargo, los espesantes, se comercializan describiendo la viscosidad mediante descriptores cualitativos y recomendando intervalos de viscosidad arbitrarios. La viscosidad puede verse afectada durante la deglución por dos factores reológicos: la amilasa salival y la velocidad de cizalla. Ambos factores, pueden disminuir la viscosidad y por lo tanto, el ET de los espesantes. Pocos estudios han examinado otros factores reológicos distintos a la viscosidad. En consecuencia, esta tesis tiene los siguientes objetivos: 1)Describir el efecto sobre la seguridad de la deglución de dos espesantes: uno goma xantana (XG) y uno mezcla, a varios niveles de viscosidad; 2)Determinar el rango terapéutico y las dosis de viscosidad óptimas para cada fenotipo de DO; 3)Describir el efecto de la viscosidad de cizalla sobre la eficacia de deglución; 4)Describir los factores reológicos implicados en el ET de los espesantes y determinar si esta información se incluye en el etiquetado. Evaluar los riesgos del uso de descriptores cualitativos; 5)Validar en laboratorios internacionales un protocolo científico para medir la viscosidad y los factores reológicos de deglución que le afectan; 6)Evaluar la viscosidad de cizalla, deformación extensional, fuerza máxima, adhesividad y cohesión para dosis variables de espesadores y determinar su relación con la seguridad de la deglución. Este proyecto incluye 4 capítulos con la siguiente metodología y resultados: Capítulo 1 - Tres EC con datos de 327 pacientes donde se analiza el ET de 3 espesadores para varios niveles de viscosidad (100-2000 mPa·s). Los resultados mostraron que el ET presentaba un comportamiento dependiente de la viscosidad y que sólo se necesitaban dos niveles para cubrir más del 90% de la población. El residuo oral aumenta con el aumento de la viscosidad; Capítulo 2: el análisis de 10 espesantes mostró que los fabricantes recomiendan el uso de 3 niveles de viscosidad seleccionados aleatoriamente. No se identificó ninguna descripción sobre el efecto de la amilasa o la velocidad de cizalla; Capítulo 3: diseño y validación de un protocolo científico para medir la viscosidad en 4 laboratorios internacionales, con una variabilidad entre laboratorios inferior al 10%; Capítulo 4: análisis de 4 propiedades reológicas para diferentes dosis y su relación con el ET sobre la seguridad de la deglución, evaluada en 267 pacientes. Los resultados confirmaron que la viscosidad de cizalla es el principal parámetro asociado a la seguridad de la deglución. Las principales conclusiones son: 1) Los espesantes, mejoran la seguridad de la deglución mediante el aumento de la viscosidad de cizalla de una forma dosis-dependiente. 2)Se puede establecer un rango terapéutico entre 100 y 1000 mPa·s para tratar a pacientes con DO. El aumento de la viscosidad por encima de 800-1000 mPa·s no provoca mejora significativa alguna en la seguridad de la deglución; 3)El aumento de la viscosidad, está relacionado con un aumento del residuo oral. 4)El uso de descriptores cualitativos de viscosidad comporta diversos riesgos y contradicciones, que ponen en peligro la seguridad de los pacientes; 5)Se puede aplicar en todo el mundo, un protocolo reológico para medir la viscosidad de cizalla en condiciones experimentales que reproducen el comportamiento de los espesantes durante la deglución; 6)La viscosidad de cizalla es la principal variable causando el ET de los espesantes con un fuerte efecto dosis-respuesta. Oropharyngeal dysphagia (OD) is a motility disorder characterized by the difficulty to form or move a bolus from the mouth to the esophagus. Thickening products (TP) are a widely used compensatory strategy to manage patients with OD by increasing fluid viscosity. Viscosity is a rheological parameter and can be quantitatively assessed in the international system of units (Pa·s). Therapeutic effect (TE) of TP can be analyzed by clinical trials (CT), and optimal viscosity levels can be established. Nevertheless, TP are currently commercialized describing viscosity with qualitative descriptors and recommending arbitrary ranges based on consensus and not scientific evidence. Viscosity can be affected during swallowing by two main rheological factors: salivary amylase and shear rate. Both factors can decrease viscosity and thus, the TE of TP. Very few studies have examined rheological factors other than shear viscosity which might have an impact on the therapeutic effect. In consequence, this thesis has the following aims: 1)To describe the effect on safety of swallow of two xanthan-gum-based (XG) TP and a mixture (Mx) at several levels of viscosity; 2)To determine the therapeutic range and optimal viscosity doses for each OD phenotype; 3)To describe the effect of shear viscosity on efficacy of swallow; 4)To describe the rheological factors (salivary amylase and shear rate) involved in TP's TE and to determine whether this information is included on the label. To assess the risks of the use of qualitative descriptors instead of objective viscosity levels; 5)To validate in several international laboratories a scientific protocol to measure shear viscosity and the rheological swallowing factors affecting TP; 6)To assess shear viscosity, extensional deformation, maximal force, adhesiveness and cohesiveness for varying doses of TP and determine their relationship with safety of swallow assessed by videofluoroscopy. This research project includes 4 chapters with the following methodology and results: Chapter 1 - Three CT including data on 327 patients studied the TE of 3 TP for several viscosity levels (100-2000 mPa·s). Results showed that TE presented a viscosity-dependent behavior for safety of swallow and that only two viscosity levels were needed to cover more than 90% of the population. Oral residue increased with the increment of viscosity; Chapter 2 - The analysis of 10 TP showed that manufacturers recommend the use of 3 viscosity levels randomly selected without any evidence supporting their TE. No description on the amylase effect or shear rate was identified; Chapter 3 - design and validation of a scientific protocol to measure shear viscosity of TP in 4 international laboratories, including the simulation of swallowing factors with a laboratory-variability below 10%; Chapter 4 - analysis of 4 different rheological properties for different doses of TP and their relationship with the TE on safety of swallow assessed by videofluroscopy in 267 patients. Results confirmed that shear viscosity is the main parameter associated with the safety of swallow. Main conclusions from this thesis are: 1)TP improve the safety of swallow by the increment of shear viscosity in a dose-response manner in OD patients. 2)A therapeutic range can be established between 100 and 1000 mPa·s for TP to manage OD patients. Increasing viscosity above 800-1000 mPa·s did not cause any further significant improvement in safety of swallow; 3)The increment of shear viscosity is related to an increase in oral residue. 4)The use of qualitative viscosity descriptors for labeling TP leads to several risks and contradictions, jeopardizing the safety of patients; 5) A rheological protocol to measure shear viscosity in experimental conditions reproducing TP behavior during swallowing can be applied worldwide; 6)Shear viscosity is the main property causing the TE of TP with a strong dose-dependent effect on safety of swallow.

Several eucalyptus pulps (85% of cellulose) with different lignin and HexA content (unbleached, TCF and ECF) as well as cotton linters (97% of cellulose) were treated with ozone (at different pH and ozone doses) in order to modify its fibre-components. Special interest was given in the introduction of functional groups in carbohydrates. The presence of these groups was mainly identified by the chain scissions due to carbonyl groups (CSC=O) produced in cellulose during viscosity measurement. At a dose of 0.5% odp of ozone, the greatest amount of CSC=O (0.5) was created at acidic pH and with the ECF pulp, followed by the TCF (0.3) and by the unbleached (0.2). The same CSC=O (0.2) was obtained in cotton pulp. In this pulp, the ozone concentration had to be increased for the treatment to be effective. A further increase in the accessibility in both pulps was achieved by applying a washing stage between two ozone stages at 0.5% (0.5¿+¿0.5). With this treatment, the CSC=O was increased to 5.3 in the ECF, to 0.8 in the TCF and only to 0.3 in cotton. Brightness reversion and the amount of DNPH consumed were also used to verify the presence of functional groups. At 0.5¿+¿0.5, brightness reversion was increased from 16 to 55% in ECF, from 27 to 46% in TCF and from 7 to 31% in cotton. Therefore, it is shown that functional groups can be introduced by ozone in carbohydrates, but this effect strongly depends on the lignin, HexA and hemicellulose content This publication is part of the PID2020-114070RB-I00 (CELLECOPROD) project, funded by MCIN/AEI/10.13039/501100011033. Authors are grateful to Torraspapel S.A. (Zaragoza, Spain), ENCE (Pontevedra, Spain) and CELESA (Tortosa, Spain) for supplying the pulp used. Special thanks are also due to the Serra Hunter Fellow to Oriol Cusola

El siguiente trabajo final de grado tiene como objetivo representar calles de von Karman y perfiles de velocidad mediante un sistema PIV (velocimetría de imagen de partículas) con el fin de desarrollar prácticas académicas. Para ello se hacen dos estudios; un primer estudio experimental de las calles de von Karman con una instalación que se encuentra ubicada en el departamento de mecánica de fluidos de la ETSEIB (Escuela Técnica Superior de Ingeniería Industrial de Barcelona). En este estudio se analizan vectores de velocidad, líneas de corrientes e imágenes de contorno producidas para diferentes valores de Reynolds. Así como también, el valor y el sentido de rotación que experimentan sus vórtices. Para llevar a cabo este estudio se definen parámetros como la viscosidad cinemática y el caudal del flujo, luego mediante cálculos experimentales se obtiene el rango del numero de Reynolds que permite realizar el análisis en régimen laminar. También, se definen procedimientos operativos de la instalación y para los programas informáticos del sistema PIV se desarrollan guiones de prácticas basados en aprendizajes del usuario y capturas del procedimiento experimental para su posterior implementación docente. Para el segundo estudio se diseña y se construye otra instalación experimental para realizar el estudio de perfiles de velocidad en conductos. Esto debido a que la primera instalación presenta riesgos de seguridad en términos de uso docente. Para esta instalación se definen los componentes, criterios y limitaciones técnicas, seguidamente se realizan cálculos experimentales que permiten obtener el caudal necesario de la instalación y a partir de estos datos se obtiene el rango de valores de Reynolds que permiten visualizar y estudiar perfiles de velocidad en régimen laminar y turbulento. A partir de aquí se efectúa un diseño preliminar y se desarrolla un análisis de alternativas de diseño de la instalación para estudiar qué soluciones comerciales de los componentes se ajustan mejor a las limitaciones técnicas. Posteriormente, las alternativas se clasifican mediante una matriz de priorización para obtener la instalación objeto de estudio. Por último, se definen apartados de ergonomía, seguridad, mantenimiento preventivo y prevención de riesgos de la instalación.

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2022, Tutors: Aurora Hernández Machado, Hernando A. del Portillo, We develop a mathematical model to characterize Newtonian and non-Newtonian fluids and compute their viscosity. Experimental data of mice blood infected by Plasmodium yoelii is analysed in order to obtain its viscosity. A comparison between different periods of infection is made with a view to determine viscosity changes throughout the disease advance. The results are also compared with non-infected human blood viscosity values to study how malaria affects the viscosity Results successfully correlate with the already known viscoelastic changes of malaria-infected red blood cells

Spontaneous capillary imbibition is a classical problem in interfacial fluid dynamics with a broad range of applications, from microfluidics to agriculture. Here we study the duration of the cross-over between an initial linear growth of the imbibition front to the diffusive-like growth limit of Washburn's law. We show that local-resistance sources, such as the inertial resistance and the friction caused by the advancing meniscus, always limit the motion of an imbibing front. Both effects give rise to a cross-over of the growth exponent between the linear and the diffusive-like regimes. We show how this cross-over is much longer than previously thought – even longer than the time it takes the liquid to fill the porous medium. Such slowly slowing-down dynamics is likely to cause similar long cross-over phenomena in processes governed by wetting.

The rheological properties of blood depend highly on the properties of its red blood cells: concentration, membrane elasticity, and aggregation. These properties affect the viscosity of blood as well as its shear thinning behavior. Using an experimental analysis of the interface advancement of blood in a microchannel, we determine the viscosity of different samples of blood. In this work, we present two methods that successfully normalize the viscosity of blood for a single and for different donors, first according to the concentration of erythrocytes and second according to the shear rate. The proposed methodology is able to predict the health conditions of the blood samples by introducing a non-dimensional coefficient that accounts for the response to shear rate of the different donors blood samples. By means of these normalization methods, we were able to determine the differences between the red blood cells of the samples and define a range where healthy blood samples can be described by a single behavior.

The main result is a proof of the existence of a unique viscosity solution for Hamilton-Jacobi equation, where the hamiltonian is discontinuous with respect to variable, usually interpreted as the spatial one. Obtained generalized solution is continuous, but not necessarily differentiable.

Ethylammonium nitrate shows an enhanced ammonia solubility due to the formation of strong hydrogen bonds. This protic ionic liquid also shows negligible vapour pressure and shares many properties with water. These attractive features make it interesting to study the mixtures of ethylammonium nitrate with ammonia for absorption refrigeration systems. This paper reports new experimental data for viscosity and mass diffusion coefficient in ammonia/ethylammonium nitrate mixtures. Measurements were performed using a piston-type viscometer for viscosity, and Optical Digital Interferometry for diffusion coefficients. Viscosity measurements were performed at temperatures between 293.15 K and 353.15 K, over a wide concentration range. Diffusion measurements of ammonia in the ionic liquid were performed at 293.15 K and 303.15 K. Viscosity data and the mass diffusion process were described using a semi-empirical correlation and a non-equilibrium model, respectively. The models show an acceptable deviation from experimental data.

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2021, Tutor: Carles Calero Borrallo, In this work we study the dynamics of magnetic rods in viscous media under rotating magnetic fields. We analyze the rotation dynamics of a paramagnetic and a ferromagnetic rods under rotating fields with circular and elliptical polarization in the bulk of a viscous liquid using the slim-body approximation. We also simulate the same setup using molecular dynamics simulations and validate the results for the paramagnetic rod in the bulk. Since we recover the theoretical behaviour we simulate the dynamics of the paramagnetic rod in presence of a wall. We then confirm that under elliptically polarized rotating fields the paramagnetic microrod can act as a toggleable microswimmer.

This article describes the enhanced sensitivity to a viscous medium by a molecular rotor based fluorophore (RBF), TPSI I. The TPSI I molecule is designed in such a way that it consists of a rotor and a fluorophore with a p-rich bridge between them. TPSI I is a light-responsive material in solution as well as in the solid state. The structural design of the molecule allows flexible rotation and photo-induced cis-trans isomerization both in the solid state as well as in solution. These combined attributes of TPSI I are responsible for the ultrasensitive viscosity response of the new material, which was verified through the Fo ̈rster-Hoffmann equation. According to this equation, the derived 'x' value is 1.02 (x is related to the sensitivity) which is the highest among the contemporary reports for RBFs. The facts were evidenced both by experimental as well as theoretical data. The ultrasensitivity towards viscosity was further analyzed in in vitro studies by detecting the subtle changes in the alteration of intracellular viscosity in normal and cancerous cells. An alteration of intracellular viscosity in cells treated with viscosity modula- tors was also confirmed using a previously well-established viscosity measurement technique, dynamic measurement through the piezoelectric patch. Our research offers a detailed mechanism to improve viscosity sensors and an efficient probe for detecting minute changes in intracellular viscosity.

In this work, a numerical framework aimed at simulating high-viscous and viscoelastic liquid injection processes is presented. The study of fluid injection with viscoelastic properties, such as synthetic polymers, is of great importance in several industrial sectors, such as metallurgy, automotive, food and pharmaceutical products, ink jets and 3D printers. In this work, a Geometrical Volume-of-Fluid (VOF) method is used to represent the interface, while finite-volume discretizations of Navier-Stokes equations on collocated unstructured meshes are solved through a fractional step method. Viscoelastic constitutive models are used to resolve the non-Newtonian behaviours. The employed implementations allow integrating different types of constitutive equations and stabilization approaches. The test case proposed in the current work consist of the simulation of the discharge of a polymeric jet from an upper nozzle into an air-containing cavity with solid bottom. The behavior of the fluids under analysis is validated by observing the onset of fluid-buckling s tructures. This phenomenon consists in the appearance of toroidal oscillation (as coiling and folding patterns) after the jet hits the solid surface and begins to accumulate. First, low-Reynolds number (Re

—Dysphagia is a digestive disorder recognized by the World Health Organization (WHO) in the International Classification of Diseases (ICD) characterized by the difficulty in forming or moving the bolus from the mouth to the oesophagus that can cause the passage of food into the respiratory tract. Foods for people with dysphagia are prepared with products that modify viscosity to make them safer when ingested. The aim of this work is to establish the interaction between citric acid, widely used by the food industry, with different thickeners, both first and second range, in order to check whether they fulfil the functions for which they have been designed. The time stability and viscosity as a function of the hydration time of six thickeners and their behavior in the temperature range between 25 and 50 °C were determined. Thickener concentrations up to a maximum of 6% were used in combination with 3acid concentrations (0.5, 1 and 2%). In distilled water, the sedimentation of first range thickeners and the gelification of second range thickeners were checked, as well as the change from non-Newtonian to Newtonian behaviour after the hydrolysis process in both types of thickeners. In the presence of citric acid, the behaviour of both types of thickeners was analogous. Second range thickeners have been found to be much safer than first range thickeners in modifying the viscosity of liquids for people with dysphagia due to the fact that they do not sediment.

This project aims to complete the validation and improve and optimize the experimentation process to obtain a globular microstructure of Aluminum A356 using a crucible and a stir bar, to obtain results from the viscosity data. On the other hand the improvement of the processes developed to obtain this microstructure, such as heating times, and the process of obtaining the ingots. The base of the crucible has been modified, adding one with a larger surface for better stability and a reduction in possible accidents. Experimentation with the foundry has been affected due to the covid-19 pendemic and the confinement that did not allow attendance at the laboratory. Improvements have been proposed for the optimization of time when melting aluminum by parallelizing tasks and preparing castings in secondary ovens for better production in order to obtain ingots. And improvements to the stir bar cooling. The results obtained from the tests performed are positive, as they face where to go, what values to work with, and most importantly, a procedure for calibrating the machine to obtain reliable results. It is recommended to maintain a regime below 150 revolutions per minute to obtain the globular microstructure and keep the crucible without any residual water by preheating it to evaporate any drop left of water in the crucible and the mold as the combination of aluminum and water is very dangerous. Aquest projecte té com a objectiu completar la validació i millorar i optimitzar el procés d'experimentació per obtenir una microestructura globular de l'Alumini A356 utilitzant un crisol i una barra de remenar, i obtenir resultats a partir de les dades de viscositat. Per altra banda la millora dels processos desenvolupats per a l'obtenció d'aquesta microestructura, com són els temps d'escalfament, i el procés d'obtenció dels llingots. S'ha modificat la base del crisol, afegint una amb una superfície més gran per una millor estabilitat d'aquest i una reducció de possibles accidents. L'experimentació amb la fundició s'ha vist afectada degut a la pendèmia del covid-19 i el confinament que no va permètre l'asssistència al laboratori. S'ha proposat millores per a la optimització del temps a l'hora de fondre l'Alumini paral·lelitzant tasques i preparant colades en forns secundaris per una millor producció de cara a obtenció de llingots. I millores en la refrigeració de la barra de remenar. Els resultats obtinguts de les proves realitzades són positius, ja que s'encaren cap a on s'ha d'anar, amb quins valors s'ha de treballar, i el més important, un procediment de calibració de la màquina per obtenir uns resultats fiables. Es recomana mantenirun règim per sota de les 150 revolucions per minut per a la obtenció de la microestructura globular i mantenir el crisol sense cap resta d'aigua pre-escalfant-lo per evaporar qualsevol gota que quedi tant al crisol com en el motlle ja que la combinació d'aquests és molt perillosa.

We provide some spatial estimates for the nonlinear partial differential equation governing anti-plane motions in a nonlinear viscoelastic theory of Kelvin–Voigt type when the viscosity is a function of the strain rate. The spatial estimates we prove are an alternative of Phragmen–Lindelöf type. These estimates are possible when a precise balance between the elastic and viscoelastic nonlinearities holds.

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Curs: 2020, Tutor: Carlos Calero, In recent years the study of propulsion of microparticles immersed in liquids has received a lot of attention. Motivated by experiments carried out by Dr. Pietro's group, we studied the movement of a nickel magnetic filament (specifically a cylindrical microrod) immersed in a viscous uid with a bounding wall, whose propulsion method will be the application of a rotating magnetic eld. The study is divided into two parts: theoretical analysis and motion simulation. The results presented show a strong dependence between the filament/microrod velocity and the frequency and the existence of a critical frequency that we have calculated with theoretical arguments and it agrees with the simulations. Our simulations show a new regime of locomotion which was not proved in experiment.

Significance Tissues are viscoelastic in nature and their physical properties play a fundamental role in development, tumorigenesis, and wound healing. Cell response to matrix elasticity is well understood through a “molecular clutch” which engages when stiffness is sufficiently high to expose binding sites in mechanosensitive proteins. Here we show that cell response to pure viscous surfaces (i.e., with no elastic component) can be explained through the same molecular clutch. Mechanisms used by cells to sense rigidity are more universal and can be used to unveil cell interaction with complex viscoelastic environments. The research presents a tool to understand cells within tissues and in turn opens new avenues to incorporate viscosity into the design of synthetic cellular microenvironments., Cell response to matrix rigidity has been explained by the mechanical properties of the actin-talin-integrin-fibronectin clutch. Here the molecular clutch model is extended to account for cell interactions with purely viscous surfaces (i.e., without an elastic component). Supported lipid bilayers present an idealized and controllable system through which to study this concept. Using lipids of different diffusion coefficients, the mobility (i.e., surface viscosity) of the presented ligands (in this case RGD) was altered by an order of magnitude. Cell size and cytoskeletal organization were proportional to viscosity. Furthermore, there was a higher number of focal adhesions and a higher phosphorylation of FAK on less-mobile (more-viscous) surfaces. Actin retrograde flow, an indicator of the force exerted on surfaces, was also seen to be faster on more mobile surfaces. This has consequential effects on downstream molecules; the mechanosensitive YAP protein localized to the nucleus more on less-mobile (more-viscous) surfaces and differentiation of myoblast cells was enhanced on higher viscosity. This behavior was explained within the framework of the molecular clutch model, with lower viscosity leading to a low force loading rate, preventing the exposure of mechanosensitive proteins, and with a higher viscosity causing a higher force loading rate exposing these sites, activating downstream pathways. Consequently, the understanding of how viscosity (regardless of matrix stiffness) influences cell response adds a further tool to engineer materials that control cell behavior.

Determination of the retention factor of ionized compounds in microemulsion electrokinetic chromatography requires two mobility measurements at the same pH: one in the presence of the microemulsion and another in plain buffer. However, it has been observed that in some cases subtracting one mobility from another determined in a different medium leads to negative retention factors, which makes no sense from a chemical point of view. This indicates that there is some error in the process which has a direct impact when retention factors are used for further applications. Here, we evaluate how the components of the microemulsion confer different properties to the buffer medium, particularly varying the viscosity parameter (which is inversely related to mobility). Whereas sodium dodecyl sulfate, the surfactant used in the microemulsion, has little effect on the medium viscosity (only an increase of 5%-6%), the presence of 1-butanol, used as a stabilizer, increases it by around 30%. Meanwhile, heptane, which is used as an oil, provokes a slight decrease. Consequently, the mobilities obtained in the microemulsion system are shifted to higher values (less negative mobilities) compared to mobilities obtained in the aqueous buffer, and so one cannot be directly subtracted from the other. Since the microemulsion-buffer medium cannot be directly reproduced, we propose a correction that takes into account the variation of viscosities. This is determined from the electrophoretic mobility of the benzoate ion. As this ion does not interact with the microemulsion, the ratio of its mobilities (measured in plain buffer and microemulsion) is equivalent to the ratio of viscosities, and can be used as the correction factor for other measurements. Thus, mobilities in buffer and microemulsion media are placed on the same scale, overcoming the errors in retention factor determination.

Treball desenvolupat en el marc del programa "European Project Semester". Even though new systems like 3D printing start to get more viable, casting remains an important manufacturing technology. During a casting process, some segments at different spots of the material at the microscopic level are solidifying. Those are called grains, and they greatly influence the mechanical properties of the material. To increase the material properties the material science part (CDAL) of the UPC started with the development of a viscosity analysis prototype. This prototype analysis the viscosity, but the measured data is not accurate enough and the casting process doesn´t stop automatically. For this reason, the results from the previous group were analyzed and the existing inputs and outputs were described. With this information the main tasks were started, that include designing a case for the prototype, developing a viscosity model, doing research on viscosity and developing a software solution for the existing prototype. The results of those tasks lead to a safety increase through the case, an accurate viscosity analysis and an automated closed loop system to control the viscosity analysis. This system is now able to read the torque and speed values via Modbus, calculate the viscosity for various materials, include safety features, provide an interface and to enable customization through a maintenance window. Only the problems with the Festo motor control couldn`t be solved, due to the high complexity and communication problems between the devices. Further development could be to integrate the two motors into the program. To simplify that, replacing the motor and its control system is recommended. Incoming

Hydrocolloids are a group of food additives, used in the food industry and in the gastronomic field. Its purpose is to impart viscosity in aqueous systems, form gels, stabilize emulsions and suspensions, among others. The main objective of this work was to evaluate the effect of concentration and temperature on the rheological properties of some hydrocolloids (agar, alginate and pectin) for use in 3D food printing. Work has been carried out with hydrocolloid concentrations between 0,5 and 2,5% and at temperatures of 25, 30 and 35 ºC. The results obtained indicate that the process of homogenization of the sample during the formation of the gel is crucial to obtain good gelification. It is confirmed that the viscosity and the elastic limit in agar gels, alginates and pectins is proportional to the hydrocolloid concentration used and inversely proportional to the temperature analyzed during the process. The thixotropic nature of the gels, responds positively to the increase in temperature and negatively when the concentration of polymers increase. It has been observed that agar at concentrations of 1,5 and 2% at 25 ºC would be a good thickener and texturizing agent due to its high viscosity and the ease of hydrogen bonding at temperatures between 25 and 35 ºC. Pectin gels, from 2% to 25 ºC, have a great structural recovery and a considerable viscosity for their possible use in the field of 3D food printing. If the concentrations decrease at 1 and 1,5% these gels presents thickening and gelling properties at temperatures of 25 ºC. Finally, the use of alginate at concentrations of 2 and 2,5% is a good option when it comes to giving elasticity to food products and slightly increasing its viscosity. This gel stands out due to its invulnerability with respect to its rheological properties when faceing changes in concentration and temperature.

[ES] Los purés de verduras son productos recomendados en pacientes con distintas patologías orales y motoras, es el caso de la disfagia orofaríngea. Los purés suponen para estos pacientes alimentos seguros a la hora de deglutir. Sin embargo, conseguir la consistencia adecuada es difícil. La adición de determinados hidrocoloides puede ayudar a este tipo de alimentos a ajustar la consistencia y textura. Por tanto, el objetivo de esta investigación fue estudiar el impacto de los diferentes hidrocoloides en las propiedades de textura de una matriz de alimento tipo puré y estudiar la cinética de desestructuración de los purés en condiciones orales in vitro. Los hidrocoloides seleccionados para este estudio fueron, goma xantana, carboximetilcelulosa (CMC), λ-carragenato y almidón de maíz. El almidón de maíz es un espesante que se utiliza comúnmente en la elaboración de estos purés de verduras comerciales, con lo que se utilizó en esta investigación como referente en las muestras control. Se formularon 5 muestras: la muestra control contenía puré de verduras y almidón de maíz. Las otras cuatro formulaciones se elaboraron añadiendo una cantidad determinada de cada espesante a la muestra control. Se llevaron a cabo mediciones reológicas (viscosidad y caída de la viscosidad) con el fin de modular la textura de las muestras de purés en boca. La caída de la viscosidad al adicionar saliva artificial mostró que, independientemente de la viscosidad inicial similar, la velocidad de descomposición y la viscosidad aparente final en 10s-1 es diferente según el hidrocoloide, especialmente debido a la acción de la enzima salivar α-amilasa., [EN] Vegetable purées are recommended products in patients with different oral and motor pathologies, this is the case of oropharyngeal dysphagia. The purees suppose for these patients safe food to shallow. However, getting the right consistency is difficult. The addition of certain hydrocolloids can help this type of food adjust the consistency and texture. Therefore, the objective of this research was to study the impact of different hydrocolloids on the texture properties of a puree type food matrix and to study the kinetics of destructuration of purees in oral conditions in vitro. The hydrocolloids selected for this study were xanthan gum, carboxymethylcellulose (CMC), λcarrageenan and corn starch. Corn starch is a thickener which are commonly used in the production of these commercial vegetable purees, which was used in this research as a reference in the control samples. 5 samples were formulated: the control sample contained mashed vegetables and corn starch. The other four formulations were made by adding a certain amount of each thickener to the control sample. Rheological measurements (viscosity and viscosity drop) were carried out in order to modulate the texture of the puree samples in the mouth. The drop in viscosity when adding artificial saliva showed that, independently of the similar initial viscosity, the rate of decomposition and the final apparent viscosity at 10s-1 is different according to the hydrocolloid, especially due to the enzyme salivary α -amylase., [CA] Els purés de verdures són productes recomanats en pacients amb distintes patologies orals i motores, és el cas de la disfagia orofaríngia. Els purés suposen per a aquests pacients aliments segurs a l'hora de deglutir. No obstant això, aconseguir la consistència adequada és difícil. L'addició de determinats hidrocoloides pot ajudar a aquest tipus d'aliments a ajustar la consistència i textura. Per tant, l'objectiu d'aquesta investigació va ser estudiar l'impacte dels diferents hidrocoloides en les propietats de textura d'una matriu d'aliment tipus puré i estudiar la cinètica de desestructuració dels purés en condicions orals in vitro. Els hidrocoloides seleccionats per a aquest estudi van ser, goma xantana, carboximetilcelulosa (CMC) , λcarragenat i midó de dacsa. El midó de dacsa és un espessidor que s'utilitza comunament en l'elaboració d'aquests purés de verdures comercials, de manera que es va utilitzar en aquesta investigació com a referent en les mostres control. Es van formular 5 mostres: la mostra control contenia puré de verdures i midó de dacsa. Les altres quatre formulacions es van elaborar afegint una quantitat determinada de cada espessidor a la mostra control. Es van dur a terme mesuraments reològiques (viscositat i caiguda de la viscositat) a fi de modular la textura de les mostres de purés en boca. La caiguda de la viscositat a l'addicionar saliva artificial va mostrar que, independentment de la viscositat inicial semblant, la velocitat de descomposició i la viscositat aparent final en 10s-1 és diferent segons l'hidrocoloide, especialment a causa a lácció de l'enzim salivar α-amilasa.

The technology of 3D food printing is an alternative way of preparing a meal in an automatic additive way and is based primarily on the rheological properties of foods. The objective of the present study was to verify the effect of culinary treatment (microwave or boiling) on the rheological characteristics of sweet potato and evaluate their ability to obtain sweet potatoes-based foods that can be printed in 3D. The rheological properties (viscosity, thixotropy and yield stress) of the sweet potato are evaluated according to the cooking system and the concentration of hydrocolloid (agar-agar or alginate), in order to define the best combination of sweet potato additive so you can get an optimum design to be printed in 3 dimensions. For this, we have tried combination of sweet potato cooked in the microwave and boiled with concentration of agar and alginate of 0,25%, 0,5%, 1%, 1,5% and 2% for each hydrocolloid and evaluate their viscosity, yield stress and thixotropy characteristics. The results indicate that the viscosity, thixotropy and yield stress increase with the concentration of the additive used, with agar samples showing higher values. The best combinations of sweet potato additive have been according to the cooking system used: baking in the microwave with agar concentrations 1% and alginate 1% and 1,5%; for the case of boiling sweet potato the best concentration for both additives has been that of 1,5%. The 3D printing of these samples has allowed to obtain stable figures. The samples that have given better rheological results have been the majority of samples that rise with agar and with alginate 1,5% and the sample of sweet potato microwave 1%, attended to the results obtained in the 3D impression. These three combinations, according to this project, are the best combinations to obtain a food product based with sweet potato used in hydrocolloid, which can obtain a figure that have the correct formats during the printing.

Considering that potato puree is rich in starch, some of the rheological properties of this product have been studied in order to advance in new technologies such as 3D printing. The material used was the commercial purée and the effect of the preparation temperature of this purée was analyzed, comparing samples elaborated at 40ºC and 100ºC together with the effect of agar and alginate additives at different concentrations 0,2%, 0,4% and 0,6% in the parameters of viscosity, thixotropy and elastic limit. The results obtained have confirmed that the mashed potato is a non-Newtonian fluid and that the interactions between the hydra colloids (agar and alginate) and the starch granules of the mash create a network that increases the viscosity, the thixotropy and the limit elastic of the starch. According to these results, it has been seen that low concentrations of additives, inhibit the swelling of starch granules, limiting the access of water within them and, as a consequence, reduce the viscosity, thixotropy and the elastic limit of the mixtures; while higher concentrations (0.6%) generate the opposite effect. The effect of the preparation temperature of the samples on the rheological properties of the mash has also been verified; in samples prepared at 100° C the starch has gelled, while the samples prepared at 40 C, it hasn't gelled. Regardless of the concentrations of the additives, the samples prepared at 40 °C have shown values of viscosity, thixotropy and elastic limit lower than the samples prepared at 100 °C. Thus, it has been observed that both agar and alginate demonstrate their ability to affect potato mash and stabilize it. Even so, it has been seen that the agar causes a greater effect, since it is with the clearest starch granules breaking and with which higher viscosity, thixotropy and yield values are achieved. Thanks to this study, the effects that additives and different temperatures can exert on the starch structure of commercial potato mash and its rheology have been known, in order to improve the use of mashed potatoes in advanced food technologies such as it can be 3D food printing. Tenint en compte que el puré de patata és ric en midó, s'han estudiat algunes de les propietats reològiques d'aquest producte per tal d'avançar en les noves tecnologies com la impressió 3D. El material utilitzat ha estat el puré comercial i s'ha analitzat l'efecte de la temperatura de preparació d'aquest puré, comparant mostres elaborades a 40ºC i 100ºC juntament amb l'efecte dels additius agar i alginat a diferents concentracions 0,2%, 0,4% i 0,6% en els paràmetres de viscositat, tixotropia i límit elàstic. Els resultats obtinguts han confirmat que el puré de patata és un fluid no newtonià i que les interaccions entre els hidracol·loides (agar i alginat) i els grànuls de midó del puré creen una xarxa que fa que augmenti la viscositat, la tixotropia i el límit elàstic del midó. D'acord amb aquests resultats, s'ha vist que les baixes concentracions d'additius inhibeixen l'inflament dels grànuls de midó, limitant l'accés de l'aigua dins d'aquests i, com a conseqüència, redueixen la viscositat, tixotropia i el límit elàstic de les barreges; mentre que concentracions superiors (0,6%) generen l'efecte contrari. També s'ha comprovat l'efecte de la temperatura de preparació de les mostres sobre les propietats reològiques del puré, ja que a les mostres preparades a 100ºC, el midó ha gelificat, mentre que a les mostres preparades a 40ºC, no. Independentment de les concentracions dels additius, les mostres preparades a 40ºC han mostrat valors de viscositat, tixotropia i límit elàstic inferiors a les mostres preparades a 100ºC. Per tant, s'ha observat que tant l'agar com l'alginat demostren la seva capacitat d'afectar al puré de patata i d'estabilitzar-lo. Tot i així, s'ha vist que l'agar hi causa major efecte, ja que és amb el que més clara es veu la ruptura dels grànuls de midó i amb el que s'assoleixen valors de viscositat, tixotròpics i de rendiment més alts. Gràcies a aquest estudi s'han conegut els efectes que els additius i les diferents temperatures poden exercir en l'estructura del midó del puré de patata comercial i en la seva reologia per millorar l'ús del puré de patata en tecnologies alimentaries avançades com pot ser la impressió 3D d'aliments. Teniendo en cuenta que el puré de patata es rico en almidón, se han estudiado algunas de las propiedades reológicas de este producto con el fin de avanzar en las nuevas tecnologías como la impresión 3D. El material utilizado ha sido el puré comercial i se ha analizado el efecto de la temperatura de preparación de este puré, comparando muestras elaboradas a 40ºC i 100ºC junto con el efecto de los aditivos agar i alginato a diferentes concentraciones 0,2%, 0,4% i 0,6% en los parámetros de viscosidad, tixotropia y límite elástico. Los resultados obtenidos han confirmado que el puré de patata es un fluido no newtoniano y que las interacciones entre los hidra coloides (agar y alginato) y los gránulos de almidón del puré crean una red que hace que aumente la viscosidad, la tixotropía y el límite elástico del almidón. De acuerdo con estos resultados, se ha visto que las bajas concentraciones de aditivos inhiben el hinchamiento de los gránulos de almidón, limitando el acceso del agua dentro de estos y, como consecuencia, reducen la viscosidad, tixotropia y el límite elástico de las mezclas; mientas que concentraciones superiores (0,6%) generan el efecto contrario. También se ha comprobado el efecto de la temperatura de preparación de las muestras sobre les propiedades reológicas del puré, ya que las muestras preparadas a 100ºC el almidón ha gelificado, mientras que a les muestras preparadas a 40ºC, no. Independientemente de las concentraciones de los aditivos, las muestras preparadas a 40ºC han mostrado valores de viscosidad, tixotropia y límite elástico inferiores a las muestras preparadas a 100ºC. Así pues, se ha observado que tanto el agar como el alginato demuestran su capacidad de afectar al puré de patata y de estabilizarlo. Aún y así, se ha visto que el agar causa un mayor efecto, ya que es con el que más claramente se ve la ruptura de los gránulos de almidón y con el que se logran valores de viscosidad, tixotropía y de rendimiento más altos. Gracias a este estudio, se han conocido los efectos que los aditivos y las diferentes temperaturas pueden ejercer en la estructura del almidón del puré de patata comercial y en su reología, con el fin de mejorar el uso del puré de patata en tecnologías alimentarias avanzadas como puede ser la impresión 3D de alimentos.

Treballs Finals de Grau de Química, Facultat de Química, Universitat de Barcelona, Any: 2018, Tutors: Dolores Velasco Castrillo, Jaume García Amorós, This Final Degree Thesis has been focused on the synthesis and study of optical properties of different 9H-carbazole derivatives to, subsequently, keep working with these organic compounds in technologic applications such as haptic interfaces. To obtain the desired compounds, we have modified the 9H-Carbazole structure to introduce in it a bond which allows it to rotate on itself (this kind of compounds are called molecular rotors), providing it with more rigidity to make the product has rotative properties more sensitives to the viscosity environment and it has also been added some functional groups to allow the molecule to form hydrogen bonding with a protic solvent because our study is based on the study of how the compound changes its photochemical behaviour depending on the viscosity and nature of the environment where they are placed in. Synthetic routes that have been followed are very known reactions and have not been a difficulty to the researching work. The chemical structure of our synthetized compounds has been characterized through different spectroscopy techniques such as 1H-NMR, 13C-NMR, mass spectroscopy and IR that are the most common techniques used in conventional organic chemistry. It has been studied the possible interrelation between the solvent viscosity and the optical properties of the desired compounds as well as the interrelation between the solvent nature and these properties. To perform this study, some instrumental techniques have been used such as absorption and emission spectroscopy. Finally, we have observed that there is an interrelation between the fluorescence activity of the dyes and the viscosity of the environment they are placed in. But when the solvent is protic, that dependence gets lost and it behaves with an anomalous dependence

Els lligants bituminosos són els materials més versàtils, pràctics i manejables que s’utilitzen en la construcció de carreteres. Són materials cohesius, impermeabilitzants, flexibles i dúctils les propietats del quals canvien principalment per acció de la temperatura i la velocitat de les carregues aplicades. Aquestes propietats els converteixen en materials difícilment substituïbles. Les tècniques actuals de fabricació de mescles asfàltiques, conegudes comunament com a mescles asfàltiques en calent, utilitzen com a lligant betum asfàltic. Aquestes tècniques s’anomenen tècniques en calent perquè es treballen a temperatures molt altes, 180-200ºC per als àrids i 150-170ºC pel betum asfàltic. Aquestes altes temperatures comporten que el sector de la pavimentació estigui subjecte a nivells molt alts d’emissions de CO2. Cada cop més, els esforços dels tècnics i experts en la matèria estan enfocats en la reducció d’aquestes temperatures, i en conseqüència la disminució de Tn de CO2, contribuint així a que els mescles asfàltiques siguin tècniques més amigables amb el medi ambient. En aquest sentit apareixen les emulsions asfàltiques. El objectiu principal que persegueixen es la capacitat de poder moure un lligant hidrocarbonat molt pesat i viscós com és el betum a temperatura ambient. Les primeres emulsions asfàltiques neixen als anys 20 i s’utilitzen principalment com a regs asfàltics i mescles en fred. La necessitat de canviar la tècnica de pavimentació de carreteres fa que hi hagi una creixent investigació en les emulsions bituminoses. Per tal de poder ser utilitzades en mescles, les emulsions han de tenir un contingut de aigua molt baix, o el que es el mateix, una concentració de betum residual molt alt. En aquest punt apareixent les emulsions concentrades o les emulsions altament concentrades de betum en aigua. Aquest tipus de emulsions fa necessaris nous sistemes de fabricació, diferents als convencionals del molins col·loïdals, com el procés HIPR (High Internal Phase Ratio) proposat en aquesta tesis. No obstant les emulsions concentrades tenen un handicap important, són molt viscoses i per tant difícils de bombejar i emprar en obra. Una manera de disminuir aquesta viscositat es fabricant emulsions bimodals. El desenvolupament de aquesta tesis esta enfocada en la publicació de 4 articles científics relacionats amb el tema de la formulació d’emulsions concentrades de betum en aigua utilitzant el procés HIPR. Un primer article, dedicat al estat del art de la tècnica, un segon article enfocat en estudiar els paràmetres de control de formulació que influencien en la mida final de gota de la emulsió. Un tercer article on s’estudia la viscositat d’aquest tipus d’emulsions i s’incorpora la formulació d’emulsions bimodals i finalment, un quart article, on s’estudia la estabilitat a l’emmagatzematge. Los ligantes bituminosos son los materiales más versátiles, prácticos y manejables que se utilizan en la construcción de carreteras. Son materiales cohesivos, impermeabilizantes, flexibles y dúctiles las propiedades de los cuales cambian principalmente por acción de la temperatura y la velocidad de las cargas aplicadas. Estas propiedades los convierten en materiales difícilmente sustituibles. Las técnicas actuales de fabricación de mezclas asfálticas, conocidas comúnmente como mezclas asfálticas en caliente, utilizan como ligante betún asfáltico. Estas técnicas se denominan técnicas en caliente porque se trabaja a temperaturas muy altas, 180-200ºC para los áridos y 150-170ºC para el betún asfáltico. Estas altas temperaturas conllevan que el sector de la pavimentación este sujeto a niveles muy altos de emisiones de CO2. Cada vez más, los esfuerzos de los técnicos y expertos en la materia están enfocados en reducir estas altas temperaturas y disminuir las Tn de CO2 emitidas, contribuyendo así a que las mezclas asfálticas sean técnicas más amigables con el medio ambiente. En este sentido aparecen las emulsiones asfálticas. El objetivo principal que persiguen es la capacidad de poder mover un ligante hidrocarbonado muy pesado y viscoso como es el betún a temperatura ambiente. Les primeras emulsiones datan de los años 20 y se utilizaban principalmente en riegos asfalticos y mezclas en frio. La necesidad de cambiar la técnica de pavimentación de carreteras hace que haiga una creciente investigación en las emulsiones bituminosas. Para poder ser utilizadas en mezclas, las emulsiones han de tener un contenido de agua muy bajo, o lo que es lo mismo, una concentración de betún residual muy alto. En este punto aparecen las emulsiones concentradas o altamente concentradas de betún en agua. Este tipo de emulsiones hacen necesarios nuevos sistemas de fabricación, diferentes a los convencionales molinos coloidales, como el proceso HIPR (High Internal Phase Ratio) propuesto en esta tesis. Sin embargo, las emulsiones concentradas tienen un hándicap importante, son muy viscosas y por lo tanto serán difíciles de bombear y utilizar en obra. Una manera sencilla de disminuir esta viscosidad es fabricando emulsiones bimodales. El desarrollo de esta tesis está enfocada en la publicación de 4 artículos científicos relacionados con el tema de la formulación de emulsiones concentradas de betún en agua utilizando el proceso HIPR. Un primer artículo, dedicado al estado del arte de la técnica, un segundo artículo enfocado en estudiar los parámetros de control de formulación que influyen en el tamaño final de gota de la emulsión. Un tercer artículo donde se estudia la viscosidad de este tipo de emulsiones y se incorpora la formulación de emulsiones bimodales y finalmente, un cuarto artículo, donde se estudia la estabilidad al almacenamiento. Bituminous binders are the most versatile, practical and manageable materials used in road construction. They are sticky, waterproof, flexible, and ductile materials. Their properties change mainly by the action of temperature and speed of the applied loads. These properties make them difficult to replace by other materials. Current techniques for manufacturing asphalt mixtures, commonly known as hot mix asphalt, use bitumen as binder. These techniques are called hot techniques because they work at very high temperatures, 180-200 °C for the aggregates and 150-170 °C for the asphalt bitumen. These high temperatures lead to the paving sector be subject to very high levels of CO2 emissions. Increasingly, the efforts of technical people and skilled in the art are focused on reducing these high temperatures and lowing the tons of CO2 emitted, contributing to asphalt mixes techniques be more friendly to the environment. Therefore the asphalt emulsions appear. The main objective pursued is the ability to move a very heavy, viscous hydrocarbon, such as bitumen binder, at room temperature. First emulsions were produced the 20s and were mainly used in tack coats and cold mix asphalt. The need to change the paving techniques increases the research in bituminous emulsions. To be used in mixtures, emulsions must have very low water content, or what is the same, high concentration bitumen residual content. Here is where the concentrated and highly concentrated bitumen emulsions appear. Therefore, new manufacturing systems to produce such emulsions become necessary. Manufacturing systems different from conventional colloid mills, such as HIPR (High Internal Phase Ratio) method proposed in this thesis. However, concentrated emulsions have an important handicap, are very viscous and therefore will be difficult to pump and use on site. A simple way to decrease this viscosity is by manufacturing bimodal emulsions. The development of this thesis is focused on 4 scientific publications related to the formulation of concentrated bitumen in water emulsions using the HIPR method. A first article, dedicated to the state of the art of the technique, a second article focused on studying the formulation control parameters that influence the final drop size of the emulsion. A third article was the viscosity of this type of emulsions is studied and the formulation of bimodal emulsions is incorporated and finally, a fourth article, where the storage stability is studied.

[ES] En el presente trabajo se plantea evaluar la capacidad de la técnica de imagen de retrodispersión láser para caracterizar las propiedades de viscosidad de diferentes harinas de trigo, las cuales son sometidas a diferentes pretratamientos térmicos. Un pretratamiento térmico en las harinas se ha demostrado capaz de modificar las propiedades reológicas de las harinas ya que afecta a la extensibilidad del gluten, la absorción de agua y a la gelatinización del almidón, evitando el uso de otros mejoradores. Se estudian dos variedades de harina de trigo, una destinada para la elaboración de pastas y otra para la elaboración de pan. Las propiedades de viscosidad de las harinas han sido caracterizadas mediante el viscosímetro Rapid Visco Analyser (RVA). Paralelamente, se han evaluado las propiedades de viscosidad mediante la técnica de imagen para evaluar su capacidad, usando unos descriptores prediseñados a partir de la imagen obtenida cuando el haz de luz láser incide en la muestra. Una vez caracterizadas por ambos métodos, y con la finalidad de poder visualizar en su conjunto los descriptores y los datos para cada una de las harinas, en función del pretratamiento térmico, se llevaron a cabo dos estudios separados de análisis de componentes principales (PCA), uno para cada método. Pese a las similitudes en la tendencia de la evolución de los datos de varianza y en la distribución de los datos en el espacio de varianza fisicoquímico y de imagen, no ha sido posible correlacionar ambos ensayos mediante las diversas herramientas estadísticas usadas. La técnica de imagen de retrodispersión de luz láser no ha sido capaz de modelizar y evaluar los cambios generados en la matriz alimentaria. Sin embargo, tanto la técnica de imagen como el ensayo RVA han sido capaces de distinguir entre las variedades de harinas, en función o no de su termoestabilidad, y en el caso de la harina destinada a la elaboración de pasta, ha podido diferenciar entre los distintos pretratamientos térmicos a los que se ha sometido., [EN] In the present study it is proposed to evaluate the capacity of laser backscattering imaging technique to characterize the viscosity properties of various wheat flours, which are submitted to a heat pre-treatment. Applying a heat pre-treatment to a wheat flour has been proved capable to modify the rheological properties of flours as it affects gluten extensibility, water absorption and starch gelatinization, being the use of bread improvers avoided. Two varieties of wheat flour are studied, one of them intended for use in the preparation of paste and the other for the preparation of bread. Wheat flour’s viscosity properties has been characterized through the Rapid Visco Analyser (RVA) viscometer. Simultaneously, wheat flour’s viscosity properties have been evaluated through imaging technique to evaluate its capacity, using predesigned descriptors made from the image obtained when the laser beam hits the sample. Once characterized by both methods, and to visualize the descriptors and the data for each flour, depending on the heat pretreatment, two separated principal component analysis (PCA) studies were carried out, one for each method. Despite the similarities in the evolution trend of the variance data and in the data distribution in both the physicochemical and imaging variance space, it has not been possible to correlate both assays through the diverse statistical tools used. Laser backscattering imaging technique has not been able to model and evaluate the generated changes in the food matrix. Nevertheless, both the imaging technique and the test RVA have been able to discriminate between the flour varieties, depending or not on its thermostability. In the case of the flour intended for using in the preparation of paste, it has been possible to differentiate between the diverse heat pre-treatments it has been submitted to., [CA] En el present treball es planteja avaluar la capacitat de la tècnica d’imatge de retrodispersió làser per a caracteritzar les propietats de viscositat de diverses farines de blat, les qual són sotmeses a diversos pretractaments tèrmics. Un pretractament tèrmic en les farines s’ha demostrat capaç de modificar les propietats reològiques de les farines perquè afecta a la extensibilitat del gluten, a l’absorció de l’aigua i a la gelatinització del midó, evitant l’ús d’altres milloradors. Es van estudiar dos varietats de farina de blat, una destinada a l’elaboració de pastes i altra a l’elaboració de pa. Les propietats de viscositat de les farines ham sigut caracteritzades mitjançant el viscosímetre Rapid Visco Analyser (RVA). Paral·lelament, s’han avaluat les propietats de viscositat mitjançant la tècnica d’imatge per avaluar la seua capacitat, usant uns descriptores predissenyats a partir de la imatge obtinguda quan el feix de llum làser incideix en la mostra. Una vegada caracteritzades per tots dos mètodes, i amb la finalitat de poder visualitzar en el seu conjunt els descriptors i les dades per a cadascuna de les farines, en funció del pretractament tèrmic, es va dur a terme dos estudis separats d’anàlisi de components principals (PCA), un per a cada mètode. Malgrat les similituds en la tendència d’evolució de les dades de variància i en la distribució de les dades en l’espai de variància per als espais fisicoquímic i d’imatge, no ha sigut possible correlacionar els dos assaigs mitjançant les diverses eines estadístiques utilitzades. La tècnica d’imatge de retrodispersió de llum làser no ha sigut capaç de modelitzar i avaluar els canvis generats en la matriu alimentària. No obstant això, tant la tècnica d’imatge com l’assaig RVA han sigut capaços de distingir entre les varietats de farines, en funció o no de la seua termoestabilitat. En el cas de la farina destinada a l’elaboració de pasta, s’ha pogut diferenciar entre els diversos pretractaments tèrmics als que han sigut sotmeses.