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Strategic pre-clinical development of Riminophenazines as resistance circumventing anticancer agentsKoot, Dwayne Jonathan 26 April 2013 (has links)
Cancer is responsible for upward of 13% of human deaths. Contemporary chemotherapy of disseminated cancer is often thwarted by dose limiting systemic toxicity and by multi-drug resistance (MDR). Riminophenazines are a novel class of potential anticancer agents that possess a potent multi-mechanistic antineoplastic action. Apart from their broad action against intrinsic, non-classical resistance, Riminophenazines inhibit the action of Pgp and hypothetically all ABC transporters demonstrating their great utility against classical MDR. Considering that combination chemotherapy is the norm, the vision directing R&D efforts was that Riminophenazines could be used with benefit within many standard chemotherapeutic regimes. The strategic intent of this project was to attain improved therapeutic benefit for patients through gains in both pharmaco dynamic and pharmacokinetic specificity for cancer cells over what is currently available. Tactically, this was driven through the use of synergistic Fixed-Ratio Drug Combinations (FRDC) encapsulated within tumour-targeting Nanoparticulate Drug Delivery Systems (NDDS). Long-term aims of this R&D project were to: 1) Screen FRDC of clofazimine (B663) and the lead derivative (B4125) with etoposide, paclitaxel and vinblastine for synergistic drug interactions in vitro. 2) Design, assemble and characterize a novel nanoparticulate, synergistic, anticancer co-formulation. 3) Evaluate the in vivo safety and efficacy of the developed product/s in accordance with international regulatory guidelines. Using the median effect and combination index equations, impressive in vitro synergistic drug interactions (CI<1) were shown for various FRDC of the three standard chemotherapeutics tested (etoposide, paclitaxel and vinblastine) in combination with either B663 or B4125 against MDR neoplastic cell cultures. Considering in vitro results and with the view to advance quickly to clinical studies, the already approved clofazimine (B663) was elected as the combination partner for paclitaxel (PTX). Considering the potency and wide action of PTX, a novel coformulation (designed to circumvent drug resistance) has the potential to greatly impact upon virtually all cancer types, particularly if selectively delivered through innovative delivery systems and loco-regional administration. A passively tumour targeting, micellular NDDS system called Riminocelles™ that encapsulates a synergistic FRDC of B663 and PTX has been designed, assembled using thin film hydration methods and characterized in terms of drug loading, particle size, zeta potential, CMC and drug retention under sink conditions. An acute toxicity and a GLP repeat dose toxicity study confirmed Riminocelles to be well tolerated and safe at clinically relevant dosages whilst Taxol® (QDx7) produced statistically significant (P<0.05) weight loss within 14 days. The same study demonstrated statistically significant (P<0.05) tumour growth delays superior to that of Taxol at an equivalent PTX dosage of 10 mg/kg. Importantly, all components (amphiphiles and drugs) used in assembly of Riminocelles are already individually approved for medicinal use - this promotes accelerated development towards advanced clinical trials and successful registration. Although these results are very promising (outperforming Taxol), this system was however found in a pharmacokinetic study to suffer from in vivo thermodynamic instability due to the high concentration (abundance) of albumin present in plasma. For this reason, in vivo longevity within circulation, permitting passive tumour accumulation was not fully realized. A second NDDS called the RiminoPLUS™ imaging system was additionally developed. This lipopolymeric nanoemulsion system has successfully entrapped Lipiodol® Ultra fluid (an oil based contrast agent) within the hydrophobic core of a monodisperse particle population with a size of roughly 100 nm and a stability of one week. This formulation is therefore thought capable of CT imaging of tumour tissue and drug targeting after either intravenous or loco-regional injection. In vivo proof of the imaging concept is warranted. The results of this study serve to highlight the great potential of in vitro optimized synergistic FRDC against drug resistant cancers. Lipopolymeric micelles are an effective way to formulate multiple hydrophobic drugs for intravenous administration and present a means by which cancer can be readily targeted; provided that the delivery system possess the prerequisite in vivo stability and surface attributes. Further experiments exploring synergistic drug and biological combinations as well as “intelligent” NDDS actively guided through specific molecular recognition are called for. / Thesis (PhD)--University of Pretoria, 2012. / Pharmacology / unrestricted
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Étude de la transition entre le plasma de quarks et de gluons et la matière hadronique dans le cadre d'un modèle effectif de la QCD : le modèle Polyakov-Nambu-Jona-Lasinio / A study of the transition between quark gluon plasma and hadronic matter in an effective model of QCD : the Polyakov -- Nambu -- Jona-Lasinio modelGoessens, Grégoire 26 July 2012 (has links)
Le plasma de quarks et de gluons (QGP) est un état de la matière observe lors de la collision d'ions lourds dans les accélérateurs tels que le LHC. Il est présent à haute température et/ou à haute densité, les quarks sont alors déconfinés : libres de se mouvoir et interagissant très peu entre eux. A basse température et basse densité, les quarks sont, au contraire, confines dans les hadrons formant la matière hadronique ordinaire. La présence d'une transition entre cette phase hadronique et le QGP a des conséquences importantes que ce soit 'a haute température (expériences RHIC et LHC) ou a haute densité (expérience CBM à FAIR, étude des étoiles compactes). Une première transition de phase est liée à la brisure de la symétrie chirale. Dans la matière hadronique, cette symétrie est brisée spontanément. Elle est restaurée en augmentant la température ou la densité. Au delà de la discussion habituelle sur la transition chirale, nous utiliserons un modèle, le modèle Polyakov Nambu Jona-Lasinio permettant de décrire une deuxième transition : la transition de deconfinement. Ceci permettra de séparer le diagramme Temperature-Densité en trois phases distinctes : la phase hadronique ou les quarks sont confines et o'u la symétrie chirale est brisée, la phase du QGP ou les quarks sont d'confines et o'u la symétrie chirale est restaurée et une phase hypothétique dite quarkyonique à basse température et haute densité ou les quarks sont encore confines mais ou la symétrie chirale est restaurée. On décrira, dans un premier temps les différentes transitions à l'aide des paramètres d'ordre suivant : le condensat de quark pour la transition chirale et la boucle de Polyakov pour le déconfinement. On verra ensuite comment l'évolution des fonctions spectrales des mésons sigma et pi peut nous renseigner sur le diagramme de phase. Le critère de transition chirale sera alors la différence entre les masses de ces mésons, la masse étant prise comme étant le maximum de la fonction spectrale. Le critère de transition de deconfinement sera, quant à lui, l'écart-type de la fonction spectrale. Enfin, nous verrons comment intégrer les mésons vecteurs au modèle, en particulier le méson rho, qui pourra jouer le rôle de sonde du plasma, ses propriétés étant modifiées suivant le milieu dans lequel il est émis / The quark and gluon plasma (QGP) is a state of matter observed in the collision of heavy ions in accelerators such as the LHC. It is formed at high temperature and / or high density, quarks are then deconfined : free to move and interacting very little with each other. At low temperature and low density, the quarks are, however, confined within hadrons forming the ordinary hadronic matter. The presence of the phase transition between hadronic matter and the QGP has observable consequences whatsoever at high temperature (RHIC and LHC experiments) or high density (FAIR experience, study of compact stars). A first phase transition is linked to the chiral symmetry breaking. In hadronic matter, this symmetry is spontaneously broken. It is restored by increasing the temperature or the density. Beyond the usual discussion on the chiral transition, we use a model called Polyakov Nambu Jona-Lasinio for describing a second transition, the deconfinement transition. This allows to separate the temperature-density diagram in three distinct phases : the hadronic phase where quarks are confined and where chiral symmetry is broken, the phase of the QGP where quarks are deconfined and chiral symmetry is restored and a hypothetical phase called quarkyonic at low temperature and high density in which quarks are confined but where chiral symmetry is still restored. We will describe, at first, the various transitions using the following order parameters : the quark condensate for the chiral transition and the Polyakov loop for the deconfinement one. Then we will see how the evolution of the spectral functions of sigma and pi mesons can provide information on the phase diagram. The chiral transition criterion will be the difference between the masses of these mesons, the mass being taken as the maximum of the spectral function. And the criterion for the deconfinement transition will be the standard deviation (also called variance) of the spectral function. Finally, we discuss how the vector mesons fit in the model, especially the meson, which can act as a probe of plasma properties which are modified by the environment from which it is issued
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Bismutsubchloride mit anionischen Clustern und Bismutpolykationen - Synthese, Charakterisierung und KristallstrukturenHampel, Silke 31 January 2005 (has links)
Im Mittelpunkt dieser Arbeit standen die Darstellung und Charakterisierung ternärer Bismutsubchloride unter Einbau von Übergangsmetallen der 8., 9. und 10. Gruppe. Durch Vorlage eines hohen Chloranteils in der Synthese wurde die &quot;chemische Schere&quot; der Oxidation so stark wirksam, dass in den Verbindungen die gewünschten voneinander isolierten Cluster aus Metallatomen vorlagen. Die Verbindungen Bi12PtCl12, Bi12-xRhCl13-x, Bi12-xIrCl13-x (x &lt; 1) und Bi6,67PtCl12 wurden als Pulver und als Kristalle durch Festkörperreaktionen bei 1273 K in Quarzglasampullen hergestellt. Die schwarz glänzenden, würfelförmigen Kristalle sind luftstabil, in verdünnten Mineralsäuren und in organischen Lösungsmitteln beständig. Die Zusammensetzungen wurden mit EDX-Analysen und Röntgenbeugung am Einkristall bestimmt. Zur weiteren Charakterisierung wurden quantenchemische Rechnungen, ramanspektroskopische Untersuchungen, Messungen der magnetischen Suszeptibilität und der elektrischen Leitfähigkeit durchgeführt. Kristalle der Verbindung Bi12PtCl12 täuschen ein rhomboedrisches Kristallsystem vor, die Struktur konnte in der Raumgruppe P 1 als nahezu perfekter Inversionszwilling eines Achsendrillings gelöst werden. Auf den Eckplätzen der pseudorhomboedrischen Elementarzelle befinden sich [PtBi6Cl12]2- -Cluster und in der Mitte ein (Bi6)2+ -Polykation. Dieses (Bi6)2+ -Polykation in Form eines geöffneten Oktaeders bestätigt experimentell Vorhersagen von Kuznetsov et al. Nach den Regeln von Wade ist das Polykation mit 2 x 6 + 4 = 16 Gerüstelektronen als nido-Cluster zu verstehen. Die Schwerpunkte der Anionen und Kationen fügen sich zu einer dem CsCl-Typ analogen Anordnung zusammen. Mit einer vollständigen Besetzung aller Bismutlagen in der Mitte der Elementarzelle kann Bi12PtCl12 eine Schlüsselrolle zugeordnet werden, die sozusagen den Prototyp für diesen Strukturtyp darstellt. Die weiteren Verbindungen stellen unterbesetzte Varianten dar und können von Bi12PtCl12 abgeleitet werden. Im Verlauf der Untersuchungen zu den ternären Subchloriden in den Systemen wurden wenige Kristalle der binären Verbindung Bi7Cl10 erhalten. Die Tatsache, dass es sich um eine neue binäre Phase im recht stark untersuchten Gebiet Bismut-Chlor handelte führte zu einer neuerlichen, systematischen Überprüfung des Systems Bi/Cl. Mittels thermischer Analysen wurde das Zustandsdiagramm Bi/BiCl3 präzisiert. Bi7Cl10 zersetzt sich bereits bei 190 °C peritektoid in Bi6Cl7 und BiCl3 Bi7Cl10(s) = Bi6Cl7(s) + BiCl3(g). Das Zustandsbarogramm des binären Systems wurde über Gesamtdruckmessungen im Membran-Nullmanometer erstmalig bestimmt. Aus den Druckfunktionen der Bismutchloride sowie aus Messungen der Molwärme von Bi6Cl7 wurden die thermodynamischen Standarddaten abgeleitet. Unter Verwendung dieser Daten wurden thermodynamische Modellierungen der Festkörper-Gasphasen-Gleichgewichte durchgeführt, mit deren Hilfe die Synthese von Bi7Cl10 optimiert werden konnte. Die phasenreine Gasphasenabscheidung von Bi7Cl10 ist aufgrund der Kondensation der dominierenden Gasphasenspezies BiCl und BiCl3 im Existenzbereich der Verbindung oberhalb des Zersetzungspunktes (190 °C) nicht möglich. Im Existenzgebiet von Bi7Cl10 kommt der Transport dann wegen der resultierenden Partialdrücke unmittelbar zum Erliegen. Aus Röntgenbeugungsuntersuchungen an Einkristallen geht hervor, dass Bi7Cl10 bei Raumtemperatur in der tetragonalen Raumgruppe I 41/a c d mit a = 28,235(3) und c = 39,950(4) Å kristallisiert (Z = 64). Analog zu Bi6Cl7 = ((Bi9)5+)[(Bi3Cl14)5-] kann Bi7Cl10 unter Verdopplung der Summenformel als ((Bi9)5+)[(Bi5Cl20)5-] formuliert werden. In der Kristallstruktur sind Polykationen (Bi9)5+, welche die Gestalt zweifach überkappter trigonaler Prismen haben, in ein Chlorobismutat(III)-Raumnetzwerk [(Bi5Cl20)5-] eingebettet. Die Polykationen und das Anionennetzwerk sind deutlich voneinander separiert.
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A Case Study of Complex Metallic Alloy Phases: Structure and Disorder Phenomena of Mg-Pd CompoundsMakongo Mangan, Julien Pierre Amelie 26 January 2009 (has links)
The phase diagram of the Mg-Pd system was redetermined in the range from 50 at. % Mg to 100 at. % Mg. It contains several intermediate phases with some of them being complex metallic alloy phases (CMAs), i.e., characterized by (i) giant unit cells with more than hundred atoms, (ii) inherent disorder, (iii) the presence of a cluster substructure. Phase fields and heterogeneous equilibria of the intermediate phases β- Mg6Pd, γ-Mg57Pd13, δ-Mg56.4Pd13.6, ε-Mg306Pd77, ζ-Mg64Pd17, η-Mg3Pd, θ-Mg5Pd2, ι- Mg2Pd and κ-MgPd were determined. The first five phases are CMAs with Mackay clusters as fundamental structural units. The crystal structure of the most magnesium-rich compound β-Mg6Pd was redetermined. It was found to be more complicated than previously thought due to correlated disorder of only two atom sites in the cubic unit cell. The γ-, ε- and ζ-phases form in a small window of temperature (50 oC) and composition (3 at. %) close to 80 at. % Mg. A new structure type was assigned to Mg3Pd (Cu3P, P63cm). The single phase field of the θ-phase is caused by constitutional vacancies. The new ι-phase crystallizes with NiTi2 structure-type. / Das Phasendiagramm des Systems Mg–Pd wurde im Bereich von 50 bis 100 At.-% Mg neu bestimmt. In diesem Phasendiagramm finden sich mehrere intermediäre Phasen, darunter auch komplexe intermetallische Verbindungen (engl.: complex intermetallic alloys, CMAs). CMAs sind charakterisiert durch (i) große Elementarzellen mit mehr als einhundert Atomen, (ii) intrinsischer Fehlordnung und (iii) dem Vorhandensein einer Cluster- Substruktur. Die Phasenfelder und heterogenen Gleichgewichte der intermediären Phasen β-Mg6Pd, γ- Mg57Pd13, δ-Mg56.4Pd13.6, ε-Mg306Pd77, ζ-Mg64Pd17, η-Mg3Pd, θ-Mg5Pd2, ι-Mg2Pd und κ- MgPd wurden bestimmt. Die ersten fünf der eben genannten Phasen sind CMAs mit Mackay Clustern als fundamentales strukturelles Einheit. Alle übrigen Phasen besitzen einen einfacheren kristallografischen Aufbau. Die Kristallstruktur der Mg-reichsten Verbindung β-Mg6Pd wurde neu bestimmt und ist weitaus sich als komplizierter als bisher angenommen. Die Ausdehnung des Einphasenfeldes von β-Mg6Pd lässt sich jedoch sehr einfach mit korrelierter Fehlordnung von lediglich zwei Atomen in der kubischen Elementarzelle verstehen. Die γ-, ε-, und ζ-Phasen bilden sich in einem schmalen Temperatur- (50 °C) und Zusammensetzungsbereich (3 at. %) nahe 80 at. % Mg. Der Verbindung Mg3Pd (Cu3P, P63cm) wurde ein neuer Strukturtyp zugewiesen. Die Ausdehnung des Einphasenfeldes der θ-Phase lässt sich mit dem Einbau konstitutioneller Leerstellen erklären. Die neue ι-Phase kristallisiert im NiTi2 Strukturtyp.
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Generation of high drug loading amorphous solid dispersions by different manufacturing processes / Génération de dispersions solides amorphes à forte charge en principe actif par différents procédés de fabricationLins de Azevedo Costa, Bhianca 13 December 2018 (has links)
La principale difficulté lors de l'administration orale d'un ingrédient pharmaceutique actif (API) est de garantir que la dose clinique de l’API sera dissoute dans le volume disponible de liquides gastro-intestinaux. Toutefois, environ 40% des API sur le marché et près de 90% des molécules en cours de développement sont peu solubles dans l’eau et présentent une faible absorption par voie orale, ce qui entraîne une faible biodisponibilité. Les dispersions solides amorphes (ASD) sont considérées comme l’une des stratégies plus efficaces pour résoudre des problèmes de solubilité des principes actifs peu solubles dans l’eau et, ainsi, améliorer leur biodisponibilité orale. En dépit de leur introduction il y a plus de 50 ans comme stratégie pour améliorer l’administration orale des API, la formation et la stabilité physique des ASD font toujours l'objet de recherches approfondies. En effet, plusieurs facteurs peuvent influer sur la stabilité physique des ASD pendant le stockage, parmi lesquels la température de transition vitreuse du mélange binaire API-polymère, la solubilité apparente de l'API dans le polymère, les interactions entre l'API et le polymère et le procédé de fabrication. Cette thèse consistait en deux parties qui avaient pour objectif le développement de nouvelles formulations sous forme d’ASD d'un antirétroviral, l'Efavirenz (EFV), dispersé dans un polymère amphiphile, le Soluplus, en utilisant deux procédés différents, le séchage par atomisation (SD) et l'extrusion à chaud (HME). EFV est l’API BCS de classe II de notre choix car c’est un API qui représente un défi pour les nouvelles formulations. En effet, il a besoin d’ASD plus fortement concentrées, pour lesquelles la stabilité chimique et physique pendant le stockage et la dissolution seront essentielles. Dans le but de développer de manière rationnelle les ASDs EFV- Soluplus à forte concentration, la première partie s'est concentrée sur la construction d'un diagramme de phases EFV-Soluplus en fonction de la composition et de la température. Le diagramme de phases a été construit à partir d'une étude thermique de recristallisation d'un ASD sursaturé (85 %m EFV), générée par séchage par atomisation. À notre connaissance, il s'agit de la première étude à présenter un diagramme de phase pour ce système binaire. Ce diagramme de phases est très utile et démontre que la solubilité de l'EFV dans les solutions varie de 20 %m (25 °C) à 30 %m (40 °C). Les ASD de EFV dans le Soluplus contenant plus de 30 %m d'EFV doivent être surveillées pendant le stockage dans des conditions typiques de température. Ce diagramme de phases peut être considéré comme un outil de pré-formulation pour les chercheurs qui étudient de nouvelles ASD d'EFV dans le Soluplus afin de prédire la stabilité (thermodynamique et cinétique). Les ASD préparées par différentes techniques peuvent afficher des différences dans leurs propriétés physicochimiques. La deuxième partie de cette thèse portait sur la fabrication d’ASD par des procédés HME et SD. Cette étude montre clairement que la formation d’ASD est une stratégie de formulation utile pour améliorer la solubilité dans l'eau et la vitesse de dissolution de l'EFV à partir de mélanges binaires EFV-Soluplus. Les procédés de fabrication (HME et SD) se sont révélés efficaces pour générer des ASD dans une large gamme de compositions en EFV. L'optimisation du ratio EFV-Soluplus peut être utilisée pour adapter la libération cinétique des ASD. Le choix d’une charge EFV élevée dépassant la solubilité thermodynamique de l’EFV dans le Soluplus est possible, mais il convient de prendre en compte sa stabilité cinétique dans le temps. / The main difficulty when an Active Pharmaceutical Ingredient (API) is orally administered is to guarantee that the clinical dose of the API will be dissolved in the available volume of gastrointestinal fluids. However, about 40% of APIs with market approval and nearly 90% of molecules in the discovery pipeline are poorly water-soluble and exhibits a poor oral absorption, which leads to a weak bioavailability. Amorphous solid dispersions (ASD) are considered as one of the most effective strategies to solve solubility limitations of poorly-water soluble compounds and hence, enhance their oral bioavailability. Despite their introduction as technical strategy to enhance oral APIs bioavailability more than 50 years ago, ASD formation and physical stability remains a subject of intense research. Indeed, several factors can influence the physical storage stability of ASD, among them, the glass transition temperature of the API-carrier binary mixture, the apparent solubility of the API in the carrier, interactions between API and carrier, and the manufacturing process. This thesis consisted of two parts that aim on developing new formulations of ASD of an antiretroviral API, Efavirenz (EFV), dispersed in an amphiphilic polymer, Soluplus, by using two different processes, Spray-drying (SD) and Hot-melt extrusion (HME). EFV is the class II BCS API of our choice because it is a challenging API for new formulations. It needs higher-dosed ASDs, for which chemical and physical stability during storage and dissolution will be critical. Aiming a rational development of high-loaded EFV-Soluplus ASDs, the first part focused on the construction of a temperature- composition EFV-Soluplus phase diagram. The phase-diagram was constructed from a thermal study of recrystallization of a supersaturated ASD (85 wt% in EFV), generated by spray drying. To our knowledge, this is the first study reporting a phase-diagram for this binary system. This phase-diagram is very useful and demonstrated that the EFV solubility in Soluplus ranges from 20 wt% (25 °C) to 30 wt% (40 °C). ASD of EFV in Soluplus containing more than 30 wt% of EFV should be monitored over storage under typical temperature conditions. This phase-diagram might be considered as a preformulation tool for researchers studying novel ASD of EFV in Soluplus, to predict (thermodynamic and kinetic) stability. ASD prepared by different techniques can display differences in their physicochemical properties. The second part of this thesis focused on the manufacturing of ASD by HME or SD processes. This study clearly shows that ASD is a useful formulation strategy to improve the aqueous solubility and the dissolution rate of EFV from EFV-Soluplus binary mixtures. HME and SD manufacturing processes demonstrated to be efficient to generate ASDs in a large range of compositions and loads of EFV. The optimization of EFV to Soluplus ratio can be used to tailor the release kinetics from ASD. The choice of a high EFV load exceeding the thermodynamic solid solubility in Soluplus is possible but it needs the consideration of its kinetic stability over time.
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Azimuthal anisotropy in gold-gold collisions at 4.5 GeV center-of-mass energy per nucleon pair using fixed-target mode at the Relativistic Heavy-Ion ColliderWu, Yang 09 July 2019 (has links)
No description available.
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Investigations intothe crystallization of butyl parabenYang, Huaiyu January 2011 (has links)
In thisproject, solubility of butyl paraben in 7 puresolvents and 5 ethanol aqueous solvents has been determined at from 1 ℃to 50 ℃. Thermodynamic properties of butyl paraben have been measured by DifferentialScanning Calorimetey. Relationship between molar solubility of butyl paraben in6 pure solvents and thermodynamic properties has been analyzed. Thisrelationship suggests a method of estimating activity of solute at equilibrium fromcombining solubility data with DSC measurements. Then, activity coefficient accordingto the solubility at different temperatures can be estimated. Duringthe solubility measurements in ethanol aqueous solvents, it is found that whenbutyl paraben is added into aqueous solutions with certain proportion ethanol,solutions separates into two immiscible liquid layers in equilibrium. Water andethanol are primary in top layer, while the butyl paraben is primary in bottomlayer, but the solution turns to cloudy when two layers of solution are mixed. Theaim of this work was to present the phase behaviour of liquid-liquid-phaseseparation for (butyl paraben + water + ethanol) ternary system from 1 ℃ to 50 ℃at atmospheric pressure. Thearea of liquid-liquid-phase separation region in the ternary phase diagram increaseswith the increasing temperature from 10 ℃to 50 ℃. In thisstudy, more than several hundreds of nucleation experiments of butyl paraben havebeen investigated in ethyl acetate, propanol, acetone and 90% ethanol aqueoussolution. Induction time of butyl paraben has been determined at 3 differentsupersaturation levels in these solvents, respectively. Free energy ofnucleation, solid-liquid interfacial energy, and nuclei critical radius havebeen determined according to the classical nucleation theory. Statistical analysis ofinduction time reveals that the nucleation is a stochastic process with widevariation even at the same experiment condition. Butyl paraben nucleates most difficultlyin 90 % ethanol than in other 3 solvents, and most easily in acetone. The interfacialenergy of butyl paraben in these solvents tends to increasing with decreasemole fraction solubility in these solvents. Coolingcrystallizations with different proportions of butyl paraben, water and ethanolhave been observed by Focused Beam Reflectance Method, Parallel VirtualMachine, and On-line Infrared. The FBRM, IR curves and the PVM photos show someof the solutions appeared liquid-liquid phase separation during coolingcrystallization process. The results suggest that if solutions went throughliquid-liquid phase separation region during the cooling crystallizationprocess the distribution of crystals crystal was poor. Droplets from solutions withsame proportion butyl paraben but different proportions of water and ethanolhave been observed under microscope. Induction time of the droplets has been determinedunder the room temperature. Droplets from top layer or bottom layer of solutionwith liquid-liquid phase separation on small glass or plastic plates were alsoobserved under microscope. The microscope photos show that the opposite flows ofcloudy solution on the glass and the plastic plate before nucleation. The resultsof the cooling and evaporation crystallization experiments both revealed thatnucleation would be prevented by the liquid-liquid phase separation. / QC 20110630
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Initiation and Propagation of Localized Corrosion of Mild Steel in Marginally Sour EnvironmentsZhang, Wei January 2020 (has links)
No description available.
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Compositional Effect on Low-Temperature Transient Liquid Phase Sintering of Tin Indium Solder PasteJohn Osarugue Obamedo (11250306) 03 January 2022 (has links)
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<p>Transient liquid phase sintering (TLPS) technologies are potential low-temperature solders for
sustainable replacements of lead-based solders and high-temperature lead-free solders. Compared to solid-state sintering and lead-free solders, TLPS uses lower temperatures
and is, thus, suitable for assembling temperature-sensitive components. TLPS is a non-
equilibrium process and determining the kinetics is critical to the estimation of processing times
needed for good joining. The tin-indium (Sn-In) system with a eutectic temperature of 119°C is
being considered as the basis for a TLPS system when combined with tin. Most models of TLPS
include interdiffusion, dissolution, isothermal solidification, and homogenization and are based
on simple binary alloys without intermediate phases. The Sn-In system has two intermediate
phases and thus the reaction kinetics require additional terms in the modeling. Differential
Scanning Calorimetry (DSC) has been used to measure the response of Sn-In alloys during the
transient liquid phase reaction. Preparation of tin indium alloys for microstructural analysis is
challenging due to their very low hardness. This study uses freeze-fracturing of the tin indium
alloys to obtain sections for microstructural analysis. The combination of DSC and
microstructure analysis provides information on the reaction kinetics. It was observed that the
solid/liquid reaction does not proceed as quickly as desired, that is, substantial liquid remains
after annealing even though the overall composition is in the single-phase region in the phase
diagram. </p>
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Phytochemical Modification of Biodegradable/Biocompatible Polymer Blends with Improved Immunological ResponsesBuddhiranon, Sasiwimon 06 December 2012 (has links)
No description available.
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