As materials get reduced in size down to the nanoscale it becomes more complex to characterize them. In this regard transmission electron microscopy has been extensively used to better characterize and understand the mechanical behavior of materials at the nanoscale, although there are various contrast mechanisms that can be used in a TEM micrograph. Focusing in particular on diffraction contrast, we know that dislocation lines are interpreted based on how the displacement field of a dislocation in an infinite crystal influences contrast. However, from a practical standpoint most of the samples that are used in microscopy are of a finite size. Thus, it is important to understand the change in contrast of a screw dislocation by taking into account the effect of crystal size. A MATLAB program has been written to simulate contrast in the TEM of a screw dislocation, taking into account the modified displacement fields for finite size crystals. The effect of reducing crystal size and the effect of microscopic parameters, such as the deviation parameter and g.b diffraction conditions have been also analyzed. / text

Texture of igneous rocks, which includes size, shape and spatial distribution of grains, represents the final record of kinetic and mechanical processes operating during ascent and final emplacement of a magma. However, traditional geochemical approaches cannot assess and verify the physical processes of magma solidification, in particular, crystal nucleation and growth, textural coarsening, or mechanical crystal-melt interactions. In this work, I apply stereological methods to quantitatively characterize the textures and to interpret the crystallization history of granitic rocks in the Western Krušné hory/Erzgebirge and Vogtland. The Western Krušné hory/Erzgebirge granites consist of three suites: biotite granites (Kirchberg), muscovite-biotite microgranites (Walfischkopf), and topaz-zinnwaldite alkali- feldspar granites (Eibenstock), which consist of eight intrusive units and two aplite dyke sets. The entire granite sequence exhibits an extreme and nearly continuous differentiation range, but in detail the evolutionary trends of each suite are independent, and individual intrusive units are also clearly compositionally separated. The granites consist of 29-43 vol.% quartz, 20-30 vol. % plagioclase, 22-31 vol. % K-feldspar, 2-9 vol. % biotite, <2 vol. % muscovite, and minor topaz and apatite. All...

L'objectif de cette étude était d'étudierl'effet d’un procédé innovant de congélation assistéepar micro-ondes (CAPMO) à faible énergie sur letemps de congélation, la qualité (microstructure,texture, perte de masse, et couleur) de la pomme etde la pomme de terre. La CAPMO des pommes etdes pommes de terre a été effectuée à unepuissance micro-onde constante (167 W/kg) et unepuissance micro-ondes appliquée par créneaux (500et 667 W/kg avec 10 s de micro-ondes sur unepériode de 30 s). Les températures ont été mesuréespendant le processus de congélation et lamicrostructure a été examinée en utilisant latomographie à rayons X et les techniques de cryo-SEM. D'autres paramètres de qualité tels que latexture, la perte de masse et la couleur ont étéévalués après décongélation de l'échantillon àtempérature ambiante.Les résultats ont montré que le processus deCAPMO n’affectait pas le temps de congélation.L'application de micro-ondes pendant le processusde congélation a produit une microstructure dequalité supérieure à celle de l'échantillon témoin ; LaCAPMO a réduit de manière significative la taillemoyenne des cristaux de glace dans les échantillonsde pommes et de pommes de terre. De plus, laCAPMO de la pomme et de la pomme de terre aentrainé une perte de masse moindre. La réductionde la fermeté / dureté et du module de Young aégalement été diminué par rapport à l'échantillontémoin. La couleur n'a pas été significativementinfluencée par la CAPMO. Parmi toutes lesconditions de congélation testées, la condition microondepulsée de 667 W/kg a donné le meilleur résultaten termes de réduction de la taille des cristaux deglace et de qualité. Ces résultats prometteursindiquent donc que l’application de micro-ondespendant la congélation permettrait d’obtenir desproduits congelés de meilleure qualité. / The objective of this study was toinvestigate the effect of innovative low energymicrowave assisted freezing (MAF) on freezing time,quality attributes (microstructure, texture, drip lossand colour) of apple and potato. MAF of apples andpotatoes was performed by applying constantmicrowave power (167 W/kg) and pulsed microwavepower (500 and 667 W/kg with 10 s pulse width and20 s pulse interval) during the freezing process. Thetemperature profile was monitored during thefreezing process, and the microstructure wasexamined using X-ray tomography and cryo-SEMtechniques. Other quality parameters such astexture, drip loss and colour were evaluated afterthawing frozen sample at room temperature.Results showed that the freezing time was notaffected by the MAF process. The application ofmicrowaves during freezing process producedsuperior microstructure than the control sample; MAFsignificantly reduced the mean ice crystal size inapple and potato sample. Moreover, MAF of appleand potato resulted in a lower drip loss, meanwhile,it also led to a lower reduction in firmness/hardnessand Young's modulus value if compared to controlsample. The colour was not significantly influencedby MAF. Among all the tested freezing conditions, the667 W/kg pulsed microwave condition yielded thebest result in terms of reduction in ice crystals sizeand retention of other quality parameters. Lastly,these results indicate that the application ofmicrowave during freezing would result in higherquality frozen products.

L'étape de pré-cristallisation au sein d'un échangeur à surface raclée est une étape clé du procédé de production de crème glacée et a une forte influence sur la qualité finale du produit. Ce travail de thèse, effectué dans le cadre du projet européen CAFE, est dédié à la caractérisation et la modélisation de ce procédé de cristallisation afin de contribuer au développement d'un contrôleur. Une caractérisation expérimentale du procédé a été effectuée et a permis de déterminer l'influence des différentes variables de contrôle sur des critères tels que la fraction de glace, le diamètre moyen des particules et la performance énergétique du procédé. Un modèle dynamique adapté au contrôle, basé sur la résolution du bilan de population par la méthode des moments, a été développé et a été validé expérimentalement. Enfin, une analyse du coût énergétique et des pistes d'améliorations de la performance sont également proposées. / Freezing is an important step in the manufacturing process of ice-cream and sorbet, since the operating conditions have a strong influence on the micro-structure, and consequently on the sensorial attributes of the final product. This work presents an experimental characterization of a continuous sorbet crystallization process in a scraped surface heat exchanger. The influence of the operating conditions on the final product characteristics (ice fraction, ice crystal size) and energy consumption have been characterized. A modeling approach of the crystallization process based on the moments method coupled with a dynamic model of the refrigerating system is proposed. The global model has been validated with experimental data, and a strategy of energy optimization taking into account the final quality of the product is finally presented.

This thesis describes the development of an empirical model of focus beam reflectance measurements (FBRM) and the application of the model to monitoring batch cooling crystallization and extracting information on crystallization kinetics. Batch crystallization is widely used in the fine chemical and pharmaceutical industries to purify and separate solid products. The crystal size distribution (CSD) of the final product greatly influences the product characteristics, such as purity, stability, and bioavailability. It also has a great effect on downstream processing. To achieve a desired CSD of the final product, batch crystallization processes need to be monitored, understood, and controlled. FBRM is a promising technique for in situ determination of the CSD. It is based on scattering of laser light and provides a chord-length distribution (CLD), which is a complex function of crystal geometry. In this thesis, an empirical correlation between CSDs and CLDs is established and applied in place of existing first-principles FBRM models. Built from experimental data, the empirical mapping of CSD and CLD is advantageous in representing some effects that are difficult to quantify by mathematical and physical expressions. The developed model enables computation of the CSD from measured CLDs, which can be followed during the evolution of the crystal population during batch cooling crystallization processes. Paracetamol, a common drug product also known as acetaminophen, is selected as the model compound in this thesis study. The empirical model was first established and verified in a paracetamol-nonsolvent (toluene) slurry, and later applied to the paracetamol-ethanol crystallization system. Complementary to the FBRM measurements, solute concentrations in the liquid phase were determined by in situ infrared spectra, and they were jointly implemented to monitor the crystallization process. The framework of measuring the CSD and the solute concentration allows the estimation of crystallization kinetics, including those for primary nucleation, secondary nucleation, and crystal growth. These parameters were determined simultaneously by fitting the full population balance model to process measurements obtained from multiple unseeded paracetamol-ethanol crystallization runs. The major contributions of this thesis study are (1) providing a novel methodology for using FBRM measurements to estimate CSD; (2) development of an experimental protocol that provided data sets rich in information on crystal growth and primary and secondary nucleation; (3) interpretation of kinetics so that appropriate model parameters could be extracted from fitting population balances to experimental data; (4) identification of the potential importance of secondary nucleation relative to primary nucleation. The protocol and methods developed in this study can be applied to other systems for evaluating and improving batch crystallization processes.

To understand the complex structure of magmatic plumbing systems beneath volcanoes, one needs to study the different textures shown in the igneous rocks produced by the volcano in question. By doing this, one can get a clue of the processes that resulted in the final rock. One of the most important methods to use for studying rock samples is the Crystal Size Distribution (CSD), which can reveal a great amount of information about the history of the rock and give an insight in the journey of the crystals during their time in the magma. An extinct volcano named Chachahuén, located in Argentina, South America, was chosen for this study. Samples of rock were collected from one of its laccoliths named Cerro Bayo and was identified as hornblende-bearing dacite. The difference in crystal size was very significant in these samples, with both larger and smaller crystals embedded in the same matrix. This is interesting considering the fact that large crystals form by slow cooling of the magma while smaller crystals form as the magma cools rapidly. By studying the CSD and interpreting other textures found in samples of igneous rock, one may interpret different processes which affected the crystals, indicating what the structure of the magma chamber once looked like. / För att kunna förstå den komplexa strukturen hos magmatiska system under vulkaner måste man studera olika texturer som påträffas i de magmatiska bergarter producerade av vulkanen i fråga. Genom att göra detta kan man få en inblick i de processer som resulterade i den slutgiltiga bergarten. En av de viktigaste metoderna att använda sig av för att studera stenprov är kristallstorleksfördelningen (CSD), som kan avslöja en mängd viktig information om bergarten och kristallernas historia under sin färd i magman. En slocknad vulkan vid namn Chachahuén belägen i Argentina, Sydamerika, valdes ut för denna studie. Stenprover samlades från en av dess lakkoliter med namnet Cerro Bayo, och identifierades som hornblände-bärande dacit. Skillnaden i kristallstorleken var mycket markant, med både större och mindre kristaller inbäddade i samma matrix. Detta är intressant med tanke på att stora kristaller bildas under en långsam nedkylning av magma medan mindre kristaller bildas när magma kyls ner snabbt. Genom att studera CSD och tolka andra texturer som finns hos magmatiska stenprover kan man tolka olika processer som har påverkat kristallerna, vilket i sin tur indikerar hur strukturen av magmakammaren en gång såg ut.

Magíster en Ciencias, Mención Geología / Geólogo / El presente trabajo presenta un nuevo método para desarrollar Crystal Size Distributions (CSD), un tipo de análisis textural cuantitativo que compara la densidad de población de cristales respecto a su tamaño. Basado en la modelación de la curva de distribución acumulada del tamaño de cristales a través de una función error, se obtienen CSD los que permiten calcular tasas de crecimiento y nucleación de distribución gaussiana asimétrica con respecto al tiempo. Este procedimiento fue aplicado en una muestra de la erupción de 1971 del volcán Villarrica entregando el tamaño límite que distingue microlitos de fenocristales y mostrando un fuerte incremento de las tasas de crecimientos y nucleación de cristales en 2 y 8 órdenes de magnitud, respectivamente, producto del ascenso de magma y cristalización en superficie. Este procedimiento también fue aplicado en cuarzo-monzodioritas del Plutón La Gloria, entregando una distribución sigmoidal de la fracción volumétrica de cristales con respecto al tiempo la que puede ser dividida en 3 etapas diferentes: una primera que muestra un muy bajo incrementos de la fracción volumétrica, la cual coincide con el pico de la tasa de crecimiento, una segunda que muestra un alto incremento de la fracción volumétrica, la cual coincide con el pico de la tasa de nucleación y una tercera que muestra una segunda disminución debido al bajo volumen disponible para nuclear nuevos cristales y recrecer antiguos. A pesar de los aportes que genera este nuevo método, el CSD seguiría siendo insuficiente para identificar distintos procesos magmáticos tales como ascenso de magma respecto a cristalización en superficie o mezcla de magmas, calentamientos o sistemas multireservorios. Es por esto que se acoplan los parámetros cinéticos de cristalización calculados a partir de CSD con la composición de plagioclasas ya que ambos dependen tanto de la temperatura como de la presión de agua. El modelo de acoplamiento es aplicado a la erupción de 1915 del Volcán Lassen Peak. Se registran dos procesos de calentamiento previo a la erupción, el segundo producto de mezcla de magmas dacíticos y andesíticos. Se registran condiciones estables del reservorio dacítico a presión de agua de 200 MPa, 830 ºC generando plagioclasas de contenido de anortita alrededor de 0.37 con lo que se infiere una cota mínima de profundidad del reservorio de 7 km. Posterior al calentamiento se registra una etapa de devolatilización a una temperatura estable de 940 ºC y el ascenso de magma el cual ocurriría en 18 horas.

Zeolitic imidazolate frameworks (ZIFs) is a new class of metal-organic frameworks (MOFs) with zeolite-like properties such as permanent porosity, uniform pore size, and exceptional thermal and chemical stability. Until recently, ZIF materials have been mostly synthesized by solvothermal method. In this thesis, further analysis to tune the size and morphology of ZIF-8 is done upon our group’s recent success in preparing ZIF-8 crystals in pure aqueous solutions. Compositional parameters (molar ratio of 2-methylimidazole/Zn2+, type of zinc salt reagents, reagent concentrations, addition of surfactants) as well as process parameters (temperature and time) were systematically investigated. Upon characterizations of as-synthesized samples by X-ray powder diffraction, thermal gravimetric analysis, N2 adsorption, and field-emission scanning electron microscope, the results show that the particle size and morphology of ZIF-8 crystals are extremely sensitive to the compotional parameters of reagent concentration and addition of surfactants. The particle size and morphology of hydrothermally synthesized ZIF-8 crystals can be finely tuned; with the size ranging from 90 nm to 4 μm and the shape from truncated cubic to rhombic dodecahedron.

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京都大学 / 新制・課程博士 / 博士(理学) / 甲第24429号 / 理博第4928号 / 新制||理||1704(附属図書館) / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)准教授 三宅 亮, 教授 野口 高明, 教授 下林 典正 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM