Tesis por compendio / [ES] El flujo anular es uno de los regímenes de flujo bifásico más importantes y se caracteriza por que una fracción de líquido muy pequeña conocida como película de líquido que viaja cerca de la pared y un núcleo gaseoso. El flujo anular se puede observar durante la operación de plantas nucleares y en diferentes escenarios transitorios, aunque también en muchas otras aplicaciones industriales. La película de líquido es determinante en muchas de ellas ya que posee una alta capacidad de transferencia de masa, momento y energía. Parte de estas propiedades se deben a que la película presenta un comportamiento interfacial no linear con desarrollo de ondas interfaciales. Además, en determinadas instalaciones donde se la película de líquido actúa como refrigerante, es esencial conocer su comportamiento tanto por motivos de optimización como por razones de seguridad. Para estudiar los fundamentos del comportamiento de la película de líquido se han llevado a cabo una serie de experimentos en una instalación diseñada para generar flujo anular aire-agua en tubería circular vertical. En esta instalación se ha medido la evolución temporal del espesor de la película de líquido bajo diferentes condiciones y subrégimenes, como flujo en caída libre o flujo en cocorriente ascendente y descendente. El sistema de medida empleado se ha diseñado y construido para esta aplicación y consiste en sondas de conductancia de 3 electrodos rasantes a la pared y dispuestas en diferentes partes de la sección de test. Tanto el sistema electrónico como el dispositivo de calibración se diseñaron específicamente para trabajar con estas son-das de conductancia. La instalación cuenta con dos diámetros diferentes para poder comparar también el efecto del diámetro de la tubería así como aumentar el rango de medidas disponibles en bases de datos. Una de las características más particulares de la película de líquido son sus ondas interfaciales. Las principales ondas que se pueden diferenciar son las disturbance waves, ondas coherentes de gran calibre; y las ripple waves, ondas de pequeño tamaño, no coherentes que se generan constantemente antes de desaparecer al ser absorbidas por otras ondas. Las variables principales de la película de líquido que se han analizado en la instalación experimental son el espesor medio, la altura y frecuencia de las disturbance waves, la altura de las ripple waves y la altura de líquido no perturbado. Se han lleva-do a cabo diferentes estudios experimentales con objeto de añadir un valor adicional a las medidas. Para flujo anular descendente se ha estudiado el desarrollo de la película a través de diferentes zonas de medida y se han comparado las secciones de test de diferente diámetro. Además, múltiples correlaciones se han propuesto y los resultados se han comparado con estudios similares de otros autores. Para el análisis del flujo anular ascendente, se ha añadido un estudio del efecto de la tensión superficial en las variables de la película de líquido mediante la adición de pequeñas cantidades de 1-butanol. Es objeto de esta tesis también la modelación del flujo anular mediante análisis numérico. Los códigos de fluidodinámica computacional (CFD) son herramientas computacionales que permiten analizar el comportamiento de los fluidos. Han experimentado una fuerte evolución a lo largo de los últimos años gracias a los avances tecnológicos y los resultados que se obtienen de su correcta utilización son muy prometedores. No obstante, el flujo multifásico sigue siendo difícil de modelar y es necesario contrastar las predicciones de los códigos CFD con medidas experimentales. Por lo tanto, la fenomenología de flujo anular desarrollado se ha estudiado también mediante el código ANSYS CFX. Existe un importante vacío de conocimiento en la cuantificación de la incertidumbre (UQ) de dichos códigos CFD. Esta tesis también presenta los fundamentos del método UQ Polynomial Chaos Expansion (PCE) aplicado a dos casos prácticos. / [CA] El flux anular és un dels règims de flux bifàsic més importants i es caracteritza perquè la fracció de líquid és molt xicoteta coneguda com a pel·lícula de líquid. El flux anul·lar es pot observar durant l'operació de plantes nuclears i en diferents escenaris transitoris, encara que també en moltes altres aplicacions industrials. La pel·lícula de líquid és determinant en moltes d'elles ja que posseeix una alta capacitat de transferència de massa, moment i energia. Part d'aquestes propietats es deuen al fet que la pel·lícula presenta un comportament interfacial no linear amb desenvolupament d'ones interfacials. A més, en determinades instal·lacions on li la pel·lícula de líquid actua com a refrigerant, és essencial conéixer el seu comportament tant per motius d'optimització com per raons de seguretat. Per a estudiar els fonaments del comportament de la pel·lícula de líquid s'han dut a terme una sèrie d'experiments en una instal·lació dissenyada per a generar flux anular aïre-aigua en canonada circular vertical. En aquesta instal·lació s'ha mesurat l'evolució temporal de la grossària de la pel·lícula de líquid sota diferents condicions i subrégimenes, com a flux en caiguda lliure o flux en cocorriente ascendent i descendent. El sistema de mesura emprat s'ha dissenyat i construït per a aquesta aplicació i consisteix en sondes de conductància de 3 elèctrodes i disposades en diferents parts de la secció de test. Tant el sistema electrònic com el dispositiu de calibratge es van dissenyar específicament per a treballar amb aquestes sondes de conductància. La instal·lació compta amb dos diàmetres diferents per a poder comparar també l'efecte del diàmetre de la canonada així com augmentar el rang de mesures disponibles en bases de dades. Una de les característiques més particulars de la pel·lícula de líquid són les seues ones interfacials. Les principals ones que es poden diferenciar són les disturbance waves, ones coherents de gran calibre; i les ripple waves, ones de xicoteta grandària, no coherents que es generen constantment abans de desaparéixer en ser absorbides per altres ones. Les variables principals de la pel·lícula de líquid que s'han analitzat en la instal·lació experimental són la grossària mitjana, l'altura i freqüència de les disturbance waves, l'altura de les ripple waves i l'altura de líquid no pertorbat. S'han dut a terme diferents estudis experimentals a fi d'afegir un valor addicional a les mesures. Per a flux anul·lar descendent s'ha estudiat el desenvolupament de la pel·lícula a través de diferents zones de mesura i s'han comparat els diferents diàmetres. A més, múltiples correlacions s'han proposat i els resultats s'han comparat amb estudis similars d'altres autors. Per a l'anàlisi del flux anul·lar ascendent, s'ha afegit un estudi de l'efecte de la tensió superficial en les variables de la pel·lícula de líquid mitjançant l'addició de xicotetes quantitats de 1-butanol. És objecte d'aquesta tesi també el modelatge del flux anul·lar mitjançant anàlisi numèrica. Els codis de fluidodinámica computacional (CFD) són eines computacionals que permeten analitzar el comportament dels fluids. Han experimentat una forta evolució al llarg dels últims anys gràcies als avanços tecnològics i els resultats que s'obtenen de la seua correcta utilització són molt prometedors. No obstant això, el flux multifásico continua sent difícil de modelar i és necessari contrastar les prediccions dels codis CFD amb mesures experimentals. Per tant, la fenomenologia de flux anular desenvolupat s'ha estudiat també mitjançant el codi ANSYS CFX. Existeix un important buit de conei-xement en la quantificació de la incertesa d'aquests codis CFD. En aquesta tesi es mostren els fonaments del Polynomial Chaos Expansion (PCE) com a mètode per a calcular la incertesa dels resultats de simulació mitjançant propagació. El PCE per quadratura de Gauss-Hermite s'ha aplicat a les simulacions de dos experiments. / [EN] Annular flow is one of the most important two-phase flow regimes and is characterized by a very small liquid fraction known as a liquid film travelling close to the wall and a gas core. Annular flow can be observed during the operation of nuclear plants, in different transient scenarios, and many other industrial applications. The liquid film is decisive in many of them as it has a high mass, momentum and energy transfer capacity. Many of these properties are due to the film exhibiting nonlinear interfacial behavior with the generation of interfacial waves. In addition, in certain facilities where the liquid film acts as a coolant, it is essential to know its behavior both for optimization and safety reasons. In order to study the fundamentals of the liquid film, a series of experiments have been carried out in a facility designed to generate air-water annual flow in a vertical circular pipe. In this facility, the time evolution of the liquid film thickness has been measured under different conditions and sub-regimes, such as free-fall flow or upward and downward cocurrent flow. The measurement system used has been designed and built for this application and consists of 3-electrode conductance probes mounted flush to the wall and arranged at different distances from the entrance of the test section. Both the electronics and the calibration device were specifically designed to work with these conductance probes. The facility has two different diameters to compare the effect of the pipe diameter and increase the range of measurements available in databases. One of the main characteristics of the liquid film is its interfacial waves. The two primary types of waves that can be distinguished are the disturbance waves, which are large coherent waves, and the ripple waves, small, non-coherent waves that are constantly generated before disappearing when absorbed by other waves. The main variables of the liquid film analyzed in the experimental setup are the mean film thickness, the height and frequency of the disturbance waves, the height of the ripple waves and the height of the unperturbed liquid. Different experimental studies have been carried out to add additional value to the measurements. For downward annular flow, the development of the film through different measuring zones has been studied, and the different test section diameters have been compared. In addition, multiple correlations have been proposed, and the results have been compared with similar studies by other authors. To analyze the upward annular flow, a study of the effect of surface tension on the liquid film variables by adding small amounts of 1-butanol has been added. The modelling of annular flow by numerical analysis is also the subject of this thesis. Computational Fluid Dynamics (CFD) codes are computational tools that allow the analysis of fluid behavior. They have undergone a strong evolution over the last few years thanks to technological advances, and the results obtained from their correct use are very promising. However, multiphase flow remains challenging to model, and it is necessary to contrast the predictions of CFD codes with experimental measurements. Therefore, the developed annular flow phenomenology has also been studied using the ANSYS CFX code. There is a significant knowledge gap in the uncertainty quantification of CFD codes. Some methodologies are available, although many are in the early stages or have not been explored by researchers. All applications of CFD codes in nuclear safety require extensive knowledge of the uncertainty of the predictions, so developing these methodologies is crucial. This thesis shows the fundamentals of Polynomial Chaos Expansion (PCE) as a method to calculate the uncertainty of simulation results by propagation. The PCE by Gauss-Hermite quadrature has also been applied to the simulations of two experiments: the experimental setup of this thesis, and an international benchmark. / I would like to acknowledge the support provided by the Ministerio de Economía, Industria y Competitividad and the Agencia Nacional de Investigación under the FPI grant BES-2017-080031, which provided funding for my research. / Rivera Durán, Y. (2023). Experimental and Modelling Study of Interfacial Phenomena in Annular Flow with Uncertainty Quantification [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/194606 / Compendio

<p>  </p> <p>The study of two-phase flow in different orientations can allow for greater understanding of the fundamentals of two-phase flow dynamics. While a large amount of work has been performed for vertical flows and recent work has been done for horizontal flows, limited research has been done studying inclined upward two-phase flows between those two orientations. Studying two-phase flows at various inclinations is important for developing physical models and simulations of two-phase flow systems and understanding the changes between what is observed for symmetric vertical flows and asymmetric horizontal flows. The present work seeks to systematically characterize the effects of inclination on adiabatic concurrent air-water two-phase flows in straight pipes. An experimental database is established for local and global two-phase flow parameters in a novel inclinable 25.4 mm inner diameter test facility using four-sensor conductivity probes, high speed video capabilities, a ring-type impedance meter, a pressure transducer, and a gamma densitometer. Rotatable measurement ports are employed to allow for local conductivity probe measurements across the flow profile to capture asymmetric parameter distributions during experiments without stopping the flow. Some of the major effects of inclination are investigated, including the effects on flow regime transition, bubble distribution, frictional pressure loss, and relative motion between the two phases. Flow visualization and machine-learning methods are employed to identify the transitions between flow regimes for inclined orientations, and these transitions are compared against existing theoretical flow regime transition criteria proposed in literature. The theoretical transitions in literature agree well with both methods for vertical flow, but additional work is necessary for angles between 0 degrees and 60 degrees. The effect of inclination on two-phase frictional pressure drop is explored, and a novel adaption of the Lockhart-Martinelli pressure drop correlation is proposed, which is able to predict the pressure drop for the conditions investigated with an absolute percent difference of 2.6%. To explore the relationships between orientation, void fraction, and relative motion, one-dimensional drift flux analyses are performed for the data at each angle investigated. It is observed that the relative velocity between phases decreases as the angle is reduced, with a relative velocity near zero at some intermediate angles and a negative relative velocity for near-horizontal orientations.  Existing modeling capabilities that have been developed for vertical and horizontal flows are evaluated based on the local two-phase parameters collected at multiple orientations. The performance of the one-dimensional interfacial area transport equation for vertical and horizontal flows is tested against experimental data and a novel model for horizontal and inclined-upward bubbly flows is proposed. Finally, an evaluation of existing momentum transfer relations is performed for the two-fluid model using three-dimensional computational fluid dynamics tools for horizontal and inclined. The prediction of the void fraction distribution and gas velocity profiles are compared against experimental data, and improvements to the lift force model are identified based on changes in the relative velocity between phases. </p>

This master thesis presents a theoretical investigation of the energy and stability of interfaces in iron-carbide compounds, specifically focusing on the α-Fe/Cr7C3 system. The study aims to fill the gap in knowledge regarding the surface energetics of these interfaces using Density Functional Theory (DFT). Six different α-Fe/Cr7C3 interfaceswere constructed α-Fe(001)/Cr7C3(024), α-Fe(001)/Cr7C3(202), α-Fe(001)/Cr7C3(040),α-Fe(110)/Cr7C3(024), α-Fe(110)/Cr7C3(202) and α-Fe(110)/Cr7C3(040). Due to limited computational resources, only one of them was computationally analyzed to determine its interfacial energy value. The results revealed that the interfacial energy of the α-Fe(001)/Cr7C3(040) interface falls within the range of incoherent interfaces, indicating its stability. The computed interfacial energy values ranged from 0.94 to 3.39 J/m2, consistent with similar studies on other iron interfaces. The simulations also identified minimum and local minimum points in the interface energy curve, representing stable configurations at specific interface separation distances. The presence of a minimum point at an interface separation value of d = 1.3551 Å with an interfacial energy of 0.94 J/m2 indicates the most stable configuration, while a local minimum point at d = 2.27 Å with an interfacial energy of 2.12 J/m2 suggests another stable configuration for the interface. The conclusion that the computations were correctly performed with an interfacial energy value of 0.94 J/m2 for the most stable configuration at a supercell length (aSupercell ) of 22.23 Å is drawn. The findings of this research have significant implications for future investigations and applications. Firstly, this study fills the gap of the unresearched ferrite-carbide interfaces with theoretical data. Secondly, the knowledge gained from studying these interfaces contributes to understanding hydrogen interactions, which is fundamental for the transition towards a hydrogen economy. Additionally, the incoherent nature of the interface introduces challenges in understanding material behavior and properties, necessitating further investigations for designing efficient systems. Future work includes experimental validation of the α-Fe/Cr7C3 interface to compare the theoretical and experimental energies and stability. Investigating the remaining interfaces and examining the effects of introducing hydrogen atoms in these interfaces, along with calculating the corresponding hydrogen trapping energies, are important research areas. Further advancements in understanding these interfaces can be achieved through interface engineering, multiscale modeling, and studying other iron-carbide systems. / Detta examensarbete presenterar en teoretisk undersökning av energin och stabiliteten hos gränssnitt i järnkarbidföreningar och fokuserar specifikt på α-Fe/Cr7C3-systemet. Studien syftar till att fylla kunskaps tomrummet gällande ytegenskaperna hos dessa gränssnitt genom användning av densitetsfunktionalteori (DFT). Sex olika α-Fe/Cr7C3-gränssnitt konstruerades α-Fe(001)/Cr7C3(024), α-Fe(001)/Cr7C3(202), α-Fe(001)/Cr7C3(040), α-Fe(110)/Cr7C3(024), α-Fe(110)/Cr7C3(202) och α-Fe(110)/Cr7C3(040). På grund av begränsade beräkningsresurser analyserades endast ett av dem för att bestämma dess gränssnittsenergivärde. Resultaten visade att gränssnittsenergin för α-Fe(001)/Cr7C3(040)- gränssnittet ligger inom intervallet för inkoherenta gränssnitt, vilket indikerar dess stabilitet. De beräknade gränssnittsenergivärdena varierade mellan 0,94 och 3,39 J/m2 , vilket är i linje med liknande studier där järngränssnitt studeras. Minimi och lokala minimipunkter i gränssnittets energikurva, vilket representerar stabila konfigurationer vid specifika avstånd mellan gränssnittet. Förekomsten av en minimipunkt vid ett gränssnittsavstånd på d = 1,35 Å med en gränssnittsenergi på 0,94 J/m2 indikerar den mest stabila konfigurationen, medan en lokal minimipunkt vid d = 2,27 Å med en gränssnittsenergi på 2,12 J/m2 antyder en annan stabil konfiguration för gränssnittet. Slutsatsen dras att beräkningarna utfördes korrekt med ett gränssnittsenergivärde på 0,94 J/m2 för den mest stabila konfigurationen vid en supercellslängd (aSupercell) på 22,23 Å. Fynden från denna forskning har betydande implikationer för framtida undersökningar och tillämpningar. För det första fyller denna studie kunskapsgapet gällande de otillräckligt utforskade ferrit-karbidgränssnitten med teoretisk data. För det andra bidrar den erhållna kunskapen från studiet av dessa gränssnitt till förståelsen av väteinteraktioner, vilket är grundläggande för övergången till en väteekonomi. Dessutom innebär gränssnittets inkoherenta natur utmaningar när det gäller att förstå materialbeteende och egenskaper, vilket kräver ytterligare undersökningar för att utforma effektiva system. Framtida arbete inkluderar experimentell validering av gränssnittet mellan α-Fe/Cr7C3 för att jämföra teoretiska och experimentella energier och stabilitet. Att undersöka återstående gränssnitt och undersöka effekterna av att introducera väteatomer i dessa gränssnitt och beräkna motsvarande vätefällningsenergier är viktiga forskningsområden. Gränssnittsdesign, flerskalig modellering och studier av andra järnkarbid-system kan ytterligare främja förståelsen av dessa gränssnitt.

<h4>A generalized physics-based modeling framework is presented to analyze: (a) the effects of temperature on identified degradation mechanisms, (b) interfacial debonding processes, including deterministic and stochastic mechanisms, and (c) establishing model performance benchmarks of electrochemical porous electrode theory models, as a necessary stepping stone to perform valid battery degradation analyses and designs. Specifically, the effects of temperature were incorporated into a physics-based, reduced-order model and extended for a LiCoO₂ -graphite 18650 cell. Three dimensionless driving forces were identified, controlling the temperature-dependent reversible charge capacity. The identified temperature-dependent irreversible mechanisms include homogeneous SEI, at moderate to high temperatures, and the chemomechanical degradation of the cathode at low temperatures. Also, debonding of a statistically representative electrochemically active particle from the surrounding binder-electrolyte matrix in a porous electrode was modeled analytically, for the first time. The proposed framework enables to determine the space of C-Rates and electrode particle radii that suppresses or enhances debonding and is graphically summarized into performance–microstructure maps where four debonding mechanisms were identified, and condensed into power-law relations with respect to the particle radius. Finally, in order to incorporate existing or emerging degradation models into porous electrode theory (PET) implementations, a set of benchmarks were proposed to establish a common basis to assess their physical reaches, limitations, and accuracy. Three open source models: dualfoil, MPET, and LIONSIMBA were compared, exhibiting significant qualitative differences, despite showing the same macroscopic voltage response, leading the user to different conclusions regarding the battery performance and possible degradation mechanisms of the analyzed system.</h4>

Two-dimensional conjugated metal–organic frameworks (2D c-MOFs), possessing extended π–d conjugated planar structure, are emerging as a unique class of electronic materials due to their intrinsic electrical conductivities. Taking advantage of the large-area flat surface, 2D c-MOF thin films allow facile device integration with sufficient electrode contact, high device stability, and high charge transport, thereby emerging as appealing active layers for a broad range of electronic applications. Synthesis and device investigation of thin films are of great importance for their further development, which are systematically summarized in the current review. Here, the authors firstly introduce the molecular structures of representative 2D c-MOFs and present the fundamental understanding on structure–property relationships. After that, the state-of-art synthetic methodologies toward high-quality 2D c-MOF thin films are summarized, including exfoliation and reassembly (ERA), liquid-interface-assisted synthesis (LIAS), and chemical vapor deposition (CVD). By considering the advantages of 2D c-MOF films in device integration, remarkable progress in (opto-)electronic device applications are discussed, such as field-effect transistors (FETs), chemiresistive sensors, photodetectors, superconductors, and thermoelectrics. In the end, the remained challenges about the development of 2D c-MOF films for (opto-)electronics are highlighted and possible future directions are proposed to address these challenges.

Ce travail combine l'électrochimie à l'interface liquide - liquide avec le procédé sol - gel pour la modification interfaciale avec de la silice mésoporeuse. Dans la première partie de ce travail, l’interface liquide – liquide macroscopique a été utilisée pour séparer la solution aqueuse de l'espèce de précurseur de silice hydrolysées (tétraéthoxysilane (TEOS)) de l'agent tensioactif cationique (cethyltrimethylammonium (CTA+) qui a agi comme un template et a été dissous dans le dichloroéthane. Le dépôt de matériau de silice a été déclenchée par le transfert du CTA+ à partir de la phase organique vers la phase aqueuse. CTA+ qui a transféré à la phase aqueuse a catalysé la réaction de condensation de la silice sur l’interface liquide – liquide. Le dépôt de silice à des interfaces liquide – liquide miniaturisées était la deuxième partie de ce travail. Les dépôts stables sur le côté de l'interface ont été synthétisés in situ par voie électrochimique. La stabilité mécanique des dépôts de silice permis un traitement thermique de la silice. Basé sur les techniques d’imagerie (par exemple SEM) il a été constaté que les dépôts forment des hémisphères pour des temps plus long. La réaction interfaciale a également été suivie in situ par spectroscopie Raman confocale. Caractéristiques moléculaires de l'interface ont été modifiées de manière spectaculaire une fois les espèces CTA+ ont été transférés à la phase aqueuse. Les interfaces liquide – liquide miniaturisés et modifiés ont également été évaluée avec le transfert voltampérométrique / This work combines the electrochemistry at the interface between two immiscible electrolyte solutions (ITIES) with the Sol – Gel process of silica leading to an interfacial modification with mesoporous silica using soft template. In the first part of this work the macroscopic liquid – liquid interface was employed to separate the aqueous solution of the hydrolyzed silica precursor species (tetraethoxysilane (TEOS)) from the cationic surfactant (cethyltrimethylammonium (CTA+)) dissolved in the dichloroethane. The silica material deposition was controlled by the electrochemical CTA+ transfer from the organic to the aqueous phase. Template transferred to the aqueous phase catalyzed the condensation reaction and self-assembly resulting in silica deposition at the interface. Silica deposition at the miniaturized ITIES (membranes supporting array of micrometer in diameter pores were used in this regard) was the second part of this work. Silica interfacial synthesis performed in situ resulted in stable deposits growing on the aqueous side of the interface. Mechanical stability of the supported silica deposits allowed further processing – silica material was cured. Based on imaginary techniques (e.g. SEM) it was found that deposits forms hemispheres for longer experimental time scales. Interfacial reaction was also followed with in situ confocal Raman spectroscopy. Molecular characteristics of the interface were changed dramatically once CTA+ species were transferred to the aqueous phase. Array of microITIES modified with silica was also assessed by ion transfer voltammetry

Les milieux réactionnels issus de l’étude de la réactivité de deux types de polyols, le glycérol et le diglycérol par réaction d’estérification directe avec l’acide undécylénique, catalysée par l’acide dodécylbenzène sulfonique (ADBS). Les résultats montrent que les ystèmes polyol/acide undécylénique donnent une émulsion eau dans huile (E/H). L’ajout de l’ADBS et de l’eau formée in-situ aux systèmes polyol/acide undécylénique ont permis de réduire la taille des gouttelettes de 50 μm à moins de 1 μm et d’obtenir un système organisé (micro-réacteur). L’augmentation de la température contribue à favoriser le transfert de matière dans les systèmes émulsionnés et / ou gélifiés et d’obtenir un système monophasique, homogène et structurés. L’étude de la réaction de ces systèmes avec une approche site à site (site OH / site COOH) a montré que lorsque le nombre de sites acides carboxyliques est inférieur à celui des sites hydroxyles, la synthèse est totalement sélective en esters partiels des deux polyols (glycérol et diglycérol). Les rendements sont supérieurs respectivement à 60% en esters partiels de glycérol et à 70% en esters partiels de diglycérol. La modélisation de la cinétique de synthèses et la régression des données cinétiques ont montré que la réaction est réversible d’ordre 2 et athermique. Les énergies d’activation calculées sont de 17 kcal/mol et 16 kcal/mol respectivement pour le monoundécénoate de glycérol (MUG) et le diundécénoate de glycérol (DUG). De plus, la méthodologie de recherche expérimentale a montrée que les variables (concentration en catalyseur ADBS et température) permettent d’obtenir le MUG avec un rendement de plus de 60% et une sélectivité en MUG de 80%. Ensuite, l’étude de la réactivité de la double liaison terminale du MUG en présence de deux agents oxydants pour engendrer des molécules bolaamphiphiles simples a été réalisée par H2O2 / acide formique et acide métachloroperbenzoïque (m-CPBA). Les résultats ont montré le 10,11-dihydroxy-monoundécénoate de glycérol (MUGDiol) est obtenu par oxydation au H2O2 / acide formique et le 10,11-époxy-monoundécénoate de glycérol (MUGE) par réaction d’époxydation avec la m-CPBA. L’ouverture de la fonction époxyde par des molécules aminées permet l’observation de nouvelles molécules bolaamphiphiles : le 10-hydroxy-N-11-((2-hydroxyéthyl)amino)monoundécénoate de glycérol(bola éthanolamineglycérol) et le N,N-11-(diaminobutan)-10-hydroxymonoundecanoate de glycérol (bola diaminobutaneglycérol). L’étude des propriétés physico-chimiques de ces molécules amphiphiles et bolaamphiphiles a permis de monter que toutes ces molécules sont de solvo-surfactants actifs aux interfaces et elles réduisent la tension interfaciale de l’eau jusqu’à la limite de la solubilité dans l’eau. L’adsorption des molécules ne vérifie pas le modèle de Gibbs. Le MUG et le MUDG s’auto-assemblent dans l’eau et donnent des nano-objets (vésicules et agrégats plats) et s’adsorbent sur des surfaces polaires et solides (silice et ciment). Ces deux molécules retiennent 30% et 56% molécules d’eau et le nombre de molécules d’eau fortement liée aux têtes polaires est de 21 et 49 respectivement pour le MUG et le MUDG. Pour es molécules bolaamphiphiles pures (MUGE et bola éthanolamineglycérol), elles retiennent plus de 56% de molécules d’eau et se lient à plus 53 molécules d’eau. L’ensemble de ces propriétés physico-chimiques a permis de répondre aux problématiques industrielles et de formuler un produit de cure, un agent de démoulage et un produit anti-adhérent. / This study is of the reactivity of two types of polyols (glycerol and diglycerol) by direct esterification reaction with undecylenic acid from castor oil. This reaction was catalyzed by dodecylbenzene sulfonic acid (DBSA). The first step was to study of polyol / undecylenic acid reaction systems by physico-chemical approach. The result have shown that these systems give water-in-oil (W / O) emulsion. Adding DBSA and water formed in-situ in polyol/undecylenic acid systems have reduced droplet size from 50 microns to less than 1 μm and form an organized system (micro-reactor). Increasing temperature can simplify transfers in emulsified systems and / or melted gel and to get a monophasic and homogeneous system. The only systems and aided by water formed in-situ assists the organization and structuring of gels. The reaction study of these systems was analyzed by gas chromatography. This showed that when the number of carboxylic acid function sites is less than the hydroxyl function site, synthesis is totally selective to partial esters of the two polyols (glycerol and diglycerol). The yields are higher than 60% in partial glycerol esters and 70% in partial diglycerol esters. The kinetic modeling of this synthesis and regression of kinetic data by the software GEPASI showed that the reaction follows the reversible 2 order and it is athermic. The calculated activation energy is 17 kcal/mol for the synthesis of glycerol monoundecenoate (GMU) and 16 kcal/mol for glycerol diundecenoate (GDU), these values are close to the theoretical values and they show that the reaction is happening at room temperature. Moreover, the response of the surface methodology shows that the variables chosen for the present study are temperature and catalyst concentration have a positive effect on the yield of the GMU. This approach was used to determine the optimum conditions for producing the GMU. Second study performed was of the reactivity of the terminal double bond of the GMU in presence of two oxidizing agents H 2 O 2 / formic acid and metachloroperbenzoic acid (m-CPBA), for synthesized bolaamphiphiles molecules was performed. The H 2 O 2 /formic acid was used to oxidize the double bond of GMU in diol function of glycerol 10,11-dihydroxymonoundecenoate (GMUDiol). The m-CPBA epoxidizes the double bond of GMU to give glycerol 10,11-epoxymonoundécénoate (GMUE). The opening of the epoxide function by aminoalcohol molecules are used to generate the new molecules bolaamphiphiles molecules: the bola ethanolamineglycerol and the bola diaminobutaneglycerol. The third step was the stady of the physico-chemical properties of pure amphiphilic and bolaamphiphiles molecules. The result was shown that all molecules are solvo-surfactants molecules and they are active in the interfaces (liquid/air and liquid/solid). The curves of surface tension of water do not respect the Gibbs rule. GMU and DGMU self- assemble in water and give nano-objects (vesicles and aggregates) in diluted solutions. In hydrogel, the molecules self-assemble in lamellar phase. In this lamellar phase, the amount of water retained is 56% and the number of water molecules strongly linked to the polar heads is 49 moles of water/diglycerol monoundecenoate molecule (DGMU). All these physico-chemical properties have permit to respond to industrial problems such as water retention for the curing product, self-assembly for demoulding concrete and for surface anti-adhesion and adsorption and finally foaming required for the aged bitumen regeneration. For pure bolaamphiphiles molecules (GEMU and ethanolamineglycerol bola) reduce the interfacial tension of water to the limit of the solubility of this bola molecules in water but do not provide a critical aggregation concentration (CAC). They retain more water molecules respectively between 56% and 63% water and the number of water molecules strongly bound with two polar heads groups pure bolaamphiphiles molecules is between 42 and 53.

Manipulation of ferromagnetic (FM) spins (and spin textures) using an antiferromagnet (AFM) as an active element in exchange coupled AFM/FM heterostructures is a promising branch of spintronics. Recent ground-breaking experimental demonstrations, such as electrical manipulation of the interfacial exchange coupling and FM spins, as well as ultrafast control of the interfacial exchange-coupling torque in AFM/FM heterostructures, have paved the way towards ultrafast spintronic devices for data storage and neuromorphic computing device applications.[5,6] To achieve electrical manipulation of FM spins, AFMs offer an efficient alternative to passive heavy metal electrodes (e.g., Pt, Pd, W, and Ta) for converting charge current to pure spin current. However, AFM thin films are often integrated into complex heterostructured thin film architectures resulting in chemical, structural, and magnetic disorder. The structural and magnetic disorder in AFM/FM-based spintronic devices can lead to highly undesirable properties, namely thermal dependence of the AFM anisotropy energy barrier, fluctuations in the magnetoresistance, non-linear operation, interfacial spin memory loss, extrinsic contributions to the effective magnetic damping in the adjacent FM, decrease in the effective spin Hall angle, atypical magnetotransport phenomena and distorted interfacial spin structure. Therefore, controlling the magnetic order down to the nanoscale in exchange coupled AFM/FM-based heterostructures is of fundamental importance. However, the impact of fractional variation in the magnetic order at the nanoscale on the magnetization reversal, magnetization dynamics, interfacial spin transport, and the interfacial domain structure of AFM/FM-based heterostructures remains a critical barrier. To address the aforementioned challenges, we conduct a comprehensive experimental investigation of chemical, structural, magnetization reversal (integral and element-specific), magnetization dynamics, and magnetotransport properties, combined with high-resolution magnetic imaging of the exchange coupled Ni3Fe/IrMn3-based heterostructures. Initially, we study the chemical, structural, electrical, and magnetic properties of epitaxially textured MgO(001)/IrMn3(0-35 nm)/Ni3Fe(15 nm)/Al2O3(2.0 nm) heterostructures. We reveal the impact of magnetic field annealing on the interdiffusion at the IrMn3/Ni3Fe interface, electrical resistivity, and magnetic properties of the heterostructures. We further present an AFM IrMn3 film thickness dependence of the exchange bias field, coercive field, magnetization reversal, and magnetization dynamics of the exchange coupled heterostructures. These experiments reveal a strong correlation between the chemical, structural and magnetic properties of the IrMn3-based heterostructures. We find a significant decrease in the spin-mixing conductance of the chemically-disordered IrMn3/Ni3Fe interface compared to the chemically-ordered counterpart. Independent of the AFM film thickness, we unveil that thermally disordered AFM grains exist in all the samples (measured up to 35-nm-thick IrMn3 films). We develop an iterative magnetic field cooling procedure to systematically manipulate the orientation of the thermally disordered and reversible AFM moments and thus, achieve tunable magnetic, and magnetotransport properties of exchange coupled AFM-based heterostructures. Subsequently, we investigate the impact of fractional variation in the AFM order on the magnetization reversal and magnetotransport properties of the epitaxially textured ɣ-phase IrMn3/Ni3Fe, Ni3Fe/IrMn3/Ni3Fe, and Ni3Fe/IrMn3/Ni3Fe/CoO heterostructures. We probe the element-specific (FM: Ni and Co, and AFM: Mn) magnetization reversal properties of the exchange coupled Ni3Fe/IrMn3/Ni3Fe/Co/CoO heterostructures in various magnetic field cooled states. We present a detailed procedure for separating the spin and orbital moment contributions for magnetic elements using the XMCD sum rule. We address whether Mauri-type domain walls can develop at the (polycrystalline) exchange coupled Ni3Fe/IrMn3/Ni3Fe interfaces. We further study the impact of magnetic field cooling on the AFM Mn (near L2,3-edges) X-ray absorption spectra. Finally, we employ a combination of in-field high-resolution magnetic force microscopy, magnetooptical Kerr effect magnetometry with micro-focused beam, and micromagnetic simulations to study the magnetic vortex structures in exchange coupled FM/AFM and AFM/FM/AFM disk structures. We examine the magnetic vortex annihilation mechanism mediated by the emergence and subsequent annihilation of the vortex-antivortex (V-AV) pairs in simple FM and exchange coupled FM/AFM as well as AFM/FM/AFM disk structures. We image the distorted magnetic vortex structures in exchange coupled FM/AFM disks proposed by Gilbert and coworkers. We further emphasize crucial magnetic vortex properties, such as handedness, effective vortex core radius, core displacement at remanence, nucleation field, annihilation field, and exchange bias field. Our experimental inquiry offers profound insight into the interfacial exchange interaction, magnetization reversal, magnetization dynamics, and interfacial spin transport of the AFM/FM-based heterostructures. Moreover, our results pave the way towards nanoscale control of the magnetic properties in AFM-based heterostructures and point towards future opportunities in the field of AFM spintronic devices.:1. Introduction 2. Magnetic Interactions and Exchange Bias Effect 3. Materials 4. Experimental Methods 5. Structural, Electrical, and Magnetization Reversal Properties of Epitaxially Textured ɣ-IrMn3/ Ni3Fe Heterostructures 6. Magnetization Dynamics of MgO(001)/IrMn3/Ni3Fe Heterostructures in the Frequency Domain 7. Tunable Magnetic and Magnetotransport Properties of MgO(001)/Ni3Fe/IrMn3/Ni3Fe/ CoO/Pt Heterostructures 8. Element-Specific XMCD Study of the Exchange Couple Ni3Fe/IrMn3/Ni3Fe/Co/CoO Heterostructures 9. Distorted Vortex Structure and Magnetic Vortex Reversal Processes in Exchange Coupled Ni3Fe/IrMn3 Disk Structures 10. Conclusions and Outlook Addendum Acronyms Symbols Publication List Author Information Acknowledgments Statement of Authorship

<p dir="ltr">Reinforced concrete elements are vulnerable to sliding against each other when shear forces are transmitted between them. Shear-friction is the mechanism by which shear is transferred between concrete surfaces. It develops by aggregate interlock between the concrete interfaces while reinforcement crossing the shear interface or normal force due to external loads contributes to the shear resistance. Current design provisions used in the United States (ACI 318-19, AASHTO LRFD (2020), and the PCI Design Handbook (2017)) include design expression for shear-friction capacity. However, the value of the reinforcement yield strength input into the expressions is limited to a maximum of 60 ksi. Furthermore, the concrete strength is not incorporated into the primary design expressions. These limits cause the potential contribution of high-strength reinforcement and high-strength concrete in shear-friction applications from being considered. Therefore, a research program was developed to investigate the possibility of improving current shear-friction design practice and addressing these current limits.</p><p dir="ltr">Specifically, an experimental program was conducted to evaluate the influence of high-strength reinforcement and high-strength concrete on shear-friction strength. In addition, a statistical analysis was performed using a comprehensive shear-frication database comprised of past tests available in the literature. The experimental program consisted of two phases. Phase I included 24 push-off specimens to study the influence of the yield strength of the interface reinforcement (Grade 60 and Grade 100) and the number and size of interface reinforcing bars (6-No.4 and 4-No. 5 bars) with three different interface conditions (rough, smooth, and shear-key). Phase II included 20 push-off specimens with rough interfaces to investigate the influence of the yield strength of the interface reinforcement (Grade 60 and Grade 100) and concrete strength (target strengths of 4000 psi and 8000 psi). The influence of these two variables was observed over a range of reinforcement ratios (ρ = 0.55%, 0.83%, 1.11%, and 1.38%).</p><p dir="ltr">The test results showed that the overall shear-friction strength was the greatest for rough interface specimens, followed by specimens detailed with shear keys. The smooth interface specimens had the lowest strengths. The results of both phases of the experimental program indicated that the use of high-strength reinforcement did not improve shear-friction capacity.</p><p dir="ltr">Furthermore, the results from the Phase II tests showed that increasing the concrete compressive strength led to increased shear-friction capacity. The test results from the experimental program were analyzed and compared with current design provisions, which demonstrated room for improvement of current design practice.</p><p dir="ltr">Following the experimental program, a comprehensive shear-friction database was analyzed, and multilinear regression was used to create a model to predict shear-friction strength. Factors were then applied to the model to provide acceptable design expressions for shear-friction strength (less than 5% unconservative estimates). The database was used to evaluate the factored model and current design provisions.</p><p dir="ltr">The research outcomes, especially the expressions for shear-friction strength that were developed and that include consideration of the concrete compression strength, along with the shear-friction tests demonstrating the lack of strength gain with the use of Grade 100 reinforcement, provide valuable information for the concrete community to help direct efforts toward improving current shear-friction design practice.</p>

In this thesis, bio-nanocomposites made from two alternative biopolymers and montmorillonite (Mnt) clay have been investigated by molecular modelling. These biopolymers are xyloglucan (XG) and chitosan (CHS), both of which are abundant, renewable, and cost-effective. After being reinforced by Mnt clay nanoparticles, the polymer nanocomposites gains in multifunctionality and in the possibility to register unique combinations of properties, like mechanical, biodegradable, electrical, thermal and gas barrier properties. I apply molecular dynamics (MD) simulations to study the interfacial mechanisms of the adhesion of these biopolymers to the Mnt nanoplatelets at an atomic level. For the XG-Mnt system, a strong binding affinity of XG to a fully hydrated Mnt interface was demonstrated. It was concluded that the dominant driving force for the interfacing is the enthalpy, i.e. the potential energy of the XG-Mnt interacting system. The adsorbed XG favors a flat conformation with a galactose residue in its side chain that facilitates the adsorption of the polymer to the nanoclay.  The XG adsorption was found do depend strongly on the hydration ability of counterions. The binding affinity of XG to Mnt was found to be strongest in the K-Mnt/XG system, followed by, in decreasing order, Na-Mnt/XG, Li-Mnt/XG, and Ca-Mnt/XG. The competing mechanism between ions, water and the XG in the interlayer region was shown to play an important role. The dimensional stability upon moisture exposure, i.e. the ability of a material to resist swelling, is an important parameter for biopolymer-clay nanocomposites. While pure clay swells significantly even at low hydration levels, it is here shown that for the XG-Mnt system, at a hydration level below 50%, the inter-lamellar spacing is well preserved, suggesting a stable material performance. However, at higher hydration levels, the XG-Mnt composite was found to exhibit swelling at the same rate as the pure hydrated Mnt clay. For the CHS-Mnt system, the significant electrostatic interactions from the direct charge-charge attraction between the polymer and the Mnt clay play a key role in the composite formation. Varying the degree of acetylation (DA) and the degree of protonation (DPr) resulted in different effects on the polymer-clay interaction. For the heavily acetylated CHS (DA &gt; 50%, also known as chitin), the strong adhesion of the neutral chitin to the Mnt clay was attributed to strong correlation between the acetyl functional groups and the counterions which act as an electrostatic “glue”. Similarly, the poor adhesion of the fully deprotonated (DPr = 0%) neutral CHS to the clay is attributed to a weak correlation between the amino functional group and the counterions. The stress-strain behavior of the CHS-Mnt composite shows that the mechanical properties are highly affected by the volume fraction of the Mnt clay and the degree of exfoliation of the composite. The material structure has a close relationship to the material properties. Biopolymer-clay nanocomposites hold a bright future to replace petroleum-derived polymer plastics and will become widely used in common life. The theme of the thesis is that further critical improvements of these materials can be accomplished by development of the experimental methods in conjunction with increased understanding of the interactions between polymer, clay, water, ions, solutions in the polymer-clay mixtures provided by molecular modelling. / I denna avhandling har molekylär modellering och molekyldynamisk (MD) simulering använts för att studera modellsystem för bio-nanokompositer bestående av montmorillonit-lera samt två olika sorters biopolymerer – xyloglukan (XG) och kitosan (CHS). Båda dessa polymerer är naturligt förekommande och mycket vanliga. De är dessutom förnyelsebara och kostnadseffektiva. Då polymererna förstärkts med nanopartiklar av montmorillonit får det resulterande kompositmaterialet en unik kombination av egenskaper såsom mekaniska, elektriska, termiska och barriär egenskaper etc. Genom att använda molekyldynamiska (MD) simuleringar, studeras här växelverkan mellan dessa biopolymerer och lernanopartiklar (Mnt) på grundläggande atomistisk detaljnivå. Mellan XG och Mnt i ett fullt hydrerat system kunde stark bindningsaffinitet påvisas. Den dominerande drivkraften för affiniteten var entalpi, d.v.s. potentiell växelverkansenergi. Den adsorberade XG-kedjan antar en platt konformation på ytan. Ett förslag utifrån simuleringsresultaten var att galaktosresidyn i xyloglukanets sidokedja underlättar adsorptionen till lerytan. Simuleringarna kunde också visa att adsorption av XG till Mnt beror starkt på motjonernas hydreringsförmåga. Bindningsaffiniteten mellan XG och Mnt var som starkast i K-Mnt/XG- systemet. Därefter följde, i minskande ordning, Na-Mnt/XG, Li-Mnt/XG och Ca-Mnt/XG. Det kunde visas att strukturen vid gränsytan styrs av konkurrerande mekanismer mellan joner, vatten och XG. Dimensionsstabilitet vid fuktexponering, d.v.s. förmågan hos ett material att motverka svällning, är en viktig egenskap för biopolymer-lernanokompositer. Ren lera sväller signifikant även vid låga fukthalter. Dock kunde MD simuleringar visa att ett modellsystem av XG-Mnt behåller sitt ursprungliga interlamellära avstånd vid hydreringsnivåer under 50%, vilket indikerar ett stabilare material. Vid högre hydrering uppmättes dock svällningen vara densamma som för ren lera. I CHS-Mnt-systemet visade det sig att direkt elektrostatisk växelverkan med signifikant styrka mellan laddningar på polymer och Mnt-yta spelar störst roll för kompositformeringen. Olika effekt på polymer-lerväxelverkan uppnåddes genom att variera acetyleringsgraden (DA) respektive protoneringsgraden (DPr). För den tungt acetylerade CHS-polymeren (DA &gt; 50%, även kallad kitin) visade sig den starka vidhäftningen bero på korrelation mellan acetylgrupperna och motjonerna som i sin tur verkade som ett elektrostatiskt “lim”. På liknande sätt kunde den svaga vidhäftningen mellan fullt deprotonerad (DPr = 0%) neutral CHS och lera förklaras med en betydligt svagare korrelation mellan aminogrupperna och motjonerna. Spänning-töjningsbeteendet hos CHS-Mnt modellen visar att dess mekaniska egenskaper beror kraftigt på volymsandelen Mnt och graden av exfoliering i kompositen. Materialets struktur är nära relaterat till materialegenskaperna. Framtiden för nanokompositer av biopolymerer och lera är ljus då de kan komma att ersätta oljebaserade plaster och användas frekvent i våra dagliga liv. Materialen kommer successivt förbättras genom utveckling av experimentella metoder i kombination med molekylmodellering för ökad förståelse för växelverkan mellan polymer, lera, vatten, joner och lösningsmedel. / 本论文利用分子动力学模拟技术研究了两种备选生物大分子与蒙脱土(Montmorillonite, Mnt)（一种粘土）组成的生物纳米复合材料，分别是木葡聚糖（Xyloglucan, XG）/蒙脱土和壳聚糖(Chitosan, CHS)/蒙脱土。木葡聚糖与壳聚糖都是自然界广泛存在的生物大分子，资源丰富且取材面宽，提取及加工成本低廉，加之可以生物降解并可再生，是优秀的生物复合材料备选原料。经过蒙脱土纳米颗粒加固后，这些基于生物大分子的复合材料将获得多功能且有多种独特特性相结合的优点，比如，更好的力学性能，生物可降解，良好的导电性能，传热性能和屏蔽气体与液体侵扰的能力等等。论文中，我们采用分子动力学模拟的方法着重对生物大分子与蒙脱土在界面上的粘附相互作用机理进行了深入探讨。  首先，对于木葡聚糖/蒙脱土纳米复合材料，我们发现糖分子与土分子间有着很强的天然亲和力。研究证明它们之间的这种相互作用，热焓是主要的推动力，也就是糖和土分子间的相互作用势能。含有半乳糖残基的木葡聚糖分子（本文中亦称天然木葡聚糖分子）吸附到粘土表面后，分子构型呈现扁平状，半乳糖残基似有辅助木葡聚糖大分子吸附到粘土颗粒上的作用。  进一步研究发现，木葡聚糖分子在粘土表面上的吸附与溶液中抗衡离子的水和作用密切相关。在钾离子平衡的糖/粘土系统中，糖分子与土分子的相互作用最强，钠离子平衡的糖/粘土系统次之，紧接着是锂离子平衡的糖/粘土系统，最弱的是钙离子平衡的糖/粘土系统。研究发现，离子，水分子，以及糖分子在粘土层间的竞争机制在糖分子的粘附过程中起着重要的作用。  材料暴露于潮湿环境中的尺寸稳定性，也就是材料抗肿胀的能力是生物大分子/蒙脱土所构成的复合材料的重要参数。蒙脱土自身即使在很低的潮湿环境下就会有明显地膨胀现象，然而，对木葡聚糖/蒙脱土复合材料来说，尺寸稳定性可以在水和值低于50%以下有效保存。其夹层尺寸的稳定保持暗示了材料在这个程度的潮湿环境下的稳定性。然而，当水和值高于50%时，木葡聚糖/蒙脱土复合材料将出现明显的肿胀现象，表现在夹层尺寸的明显增大，且其膨胀速率与粘土自身的膨胀速率逐渐趋于相当水平。  其次，对于壳聚糖/蒙脱土复合材料，我们发现由电荷-电荷间直接产生地强烈的静电吸引作用是壳聚糖分子与蒙脱土分子相互粘附并构成复合材料的关键因素。通过改变壳聚糖分子的乙酰化程度（Degree of acetylation, DA）和质子化程度(Degree of protonation, DPr)，糖分子与土分子的相互作用有着显著地不同。对于乙酰化程度（DA）高于50%的壳聚糖分子（亦成为甲壳素分子chitin, CHT），电中性的甲壳素分子与土分子间的强吸附作用源于乙酰基功能团与抗衡离子的强相关性。抗衡离子此时扮演着类似于“电子胶”的作用，可以有效地将电中性的甲壳素分子与土分子粘结在一起。类似地，当质子化程度最低时，亦即壳聚糖分子完全非质子化，即呈现电中性时，较差的糖/土吸附作用源于氨基功能团与抗衡离子的较弱的相关性。  进一步对壳聚糖/蒙脱土复合材料的分子系统进行应力应变计算发现，复合材料的力学性能直接受蒙脱土体积分数和其剥离程度的影响，通常，粘土的体积分数越大体系的力学性能越高，且剥离程度对材料的整体性能也有直接影响。因此，材料的结构与其性能的表征有着密切联系。  我们相信生物大分子与蒙脱土构成的生物复合材料有着光明的前景，可以取代石油提取物制成的塑料材料，并将能够广泛应用在日常生活中。通过实验技术的改善和应用分子模拟技术对复合材料体系中生物大分子，蒙脱土分子，水分子，离子，溶液环境等混合物质相互作用的理解增加，这种可再生的新材料将会得到重要改进，这也是整本论文的主旋律。 / <p>QC 20150520</p> / Bio-nanocomposites