Thesis (M.S. in in Aeronautical Engineering)--Air Force Institute of Technology, March 2008. / "Presented to the Faculty, Department of Aeronautics and Astronautics Graduate School of Engineering and Management, Air Force Institute of Technology Air University, Air Education and Training Command in partial fulfillment of the requirements for the Degree of Master of Science in Aeronautical Engineering, March 2008."--P. [ii]. Thesis advisor: Dr. William Hargus. "March 2008." "AFIT/GA/ENY/08-M01." Includes bibliographical references. Also available online in PDF from the DTIC Online Web site.

Defect control in colloidal crystals is essential for these nanostructures to be effective as photonic bandgap (PBG) materials. We have used in-situ monitoring of the PBG of a colloidal crystal to study the structural changes during colloidal self assembly, with a focus on the formation of macroscopic defects such as cracks. These findings allow us to model the final stages of colloidal self assembly and explain the formation of growth defects in colloidal crystal. Our model suggests that cracks are intrinsic to self assembly growth methods. . However, by tuning the interaction potential between the colloids, it is possible to minimize the cracks in colloidal crystals. / Singapore-MIT Alliance (SMA)

Le plutonium est produit dans les centrales nucléaires à partir de l’oxyde d’uranium utilisé comme combustible. Cet élément peut être détecté dans l’environnement du fait des essais nucléaires, accidents industriels, sous-marins nucléaires et déchets radioactifs. Le Pu peut ainsi être dispersé sous la forme de particules présentant différentes compositions chimiques et morphologiques, et plus particulièrement sous la forme colloïdale. La connaissance de la structure et de la réactivité de ces espèces s’avère primordiale pour la compréhension et la prédiction de leur éventuelle migration dans l’environnement. Dans ce contexte, la sonochimie est envisagée comme voie de synthèse innovante pour la préparation de suspensions colloïdales modèles de Pu. Dans un premier temps, les cinétiques de formation sonochimique de H2O2 dans l’eau pure et l’acide nitrique ont été étudiées en prévision des expérimentations en présence de Pu. L’étude du comportement du Pu(VI) en solution aqueuse sous ultrasons a, par la suite, permis de préparer des solutions de Pu(V) relativement pures et stables qui ont pu être rigoureusement caractérisées (XAFS, RMN, DFT, UV-vis, etc.). Par ailleurs, la sonolyse de solutions aqueuses de Pu(III) conduit à la formation d’un complexe polynucléaire de Pu(IV) hydrosoluble jamais reporté dans la littérature. Enfin, les études réalisées en milieu hétérogène solide-liquide ont permis de développer une voie de synthèse de colloïdes de Pu intrinsèques. Les colloïdes formés par sonolyse de PuO2 dans l’eau pure ont été comparés à des colloïdes hydrolytiques et autoradiolytiques à l’aide de nombreuses techniques de caractérisation (MET-HR, XAFS, STXM, NEXAFS, etc.). Le mécanisme de formation proposé implique la dispersion et la réduction de taille des particules d’oxyde suivi, de mécanismes rédox permettant l’accumulation de colloïdes. Les observations permettent de décrire ces colloïdes comme des particules nanométriques quasi-sphériques (7 nm sous ultrasons, contre 3 nm par hydrolyse) et monodisperses présentant une structure de type cœur/coquille composée d’un cœur de PuO2 cristallin et d’une surface de Pu(IV) hydrolysé. / Plutonium is a radioactive chemical element produced in nuclear power plants by uranium oxide fission reactions. This element has been found in the environment due to, for example, nuclear weapon testing, nuclear submarines and radioactive accidents. Pu has been dispersed under particle forms with various chemical compositions and morphologies and can potentially migrate under colloidal forms. The knowledge of the structure and reactivity of this species is of paramount importance to understand and predict their eventual migration into the environment. In this context, sonochemistry is considered as an innovative approach for the preparation of pattern Pu colloid suspensions. First, sonochemical kinetic formations of H2O2 in pure water and nitric media have been studied in prevision of experimentations with Pu. Pu(VI) behavior in sonicated aqueous solution has then been investigated for the preparation of relatively pure and stable Pu(V) solutions which have been rigorously characterized (XAFS, NMR, DFT, UV-vis, etc.). Besides, sonication of Pu(III) aqueous solutions lead to the formation of a hydrosoluble polynuclear complex of Pu(IV) never reported in the literature. Studies carried out in heterogeneous solid/liquid systems allowed to develop a synthesis method for the preparation of Pu intrinsic colloids. Colloids resulting from PuO2 sonolysis in pure water have been compared to hydrolytic and autoradiolytic colloids thanks to several characterization techniques (HR-TEM, XAFS, STXM, NEXAFS, etc.). The proposed formation mechanisms involves the dispersion and reduction of oxide particle sizes followed by redox reactions leading to accumulation of Pu colloids. Colloids can be described as quasi-spherical, monodisperse and nanometric particles (7 nm under ultrasound against 3 nm for hydrolysis) with a core/shell structure composed of a crystalline PuO2 core covered by a hydrolyzed Pu(IV) surface.

Deep geological disposal is a method of managing high level, long-­‐lived nuclear waste. It is a concept that many countries are exploring for the possibility of managing nuclear waste generated from power production. For deep geological disposal to be viable then areas where problems may surface have to be explored. Bentonite clay has been proposed as the material to be used for the backfill of the repositories. Its swelling properties ensure that it will expand to plug the bore holes that will be made for the waste, its impermeable nature restricts contact between groundwater and the waste package and its stability on a geological timescale all make it desirable as a backfill material. This project looks at the role that colloids formed from the bentonite clay could have in facilitating radionuclide transport away from a nuclear waste repository. Several radionuclides (Eu(III), U(VI), Th(IV) and Am(III)) have been considered in this research, and information from these studies will be used in the BELBaR project’s outputs, which will eventually support a disposal safety case. Ternary systems of 152Eu(III), bulk bentonite and EDTA ([Eu] = 7.9 x 10-­‐10 M; pH = 6.0 – 7.0) have been studied. Without EDTA, there was slow uptake in a two-­‐stage process, with initial rapid sorption of Eu(III) (96%), followed by slower uptake of a smaller fraction (3.0 % over a period of 1 month). The reversibility of Eu(III) binding was tested by allowing Eu(III) to sorb to bentonite for 1 – 322 days. EDTA was added to the pre-­‐equilibrated Eu bentonite systems at 0.01 M. A dissociation rate constant of approximately 4.3 x 10-­‐8 s-­‐1 (values in the range 2.2 x 10-­‐8 – 1.0 x 10-­‐7 s-­‐1) for pre-­‐equilibration times ≥ 7 days was measured. Eventually, the amount of Eu(III) remaining bound to the bentonite was within error of that when EDTA was also present prior to contact (4.5 % ± 0.6). Eu interactions with colloidal bentonite were studied, and the dissociation rate constant measured by a resin competition method. A dissociation rate of 8.8 x 10-­‐7 s-­‐1 and a range of 7.7 x 10-­‐7 – 9.5 x 10-­‐7 s-­‐1 were measured. For both bulk and colloidal bentonite slow dissociation was observed for Eu(III), but there was no evidence for ‘irreversible’ binding. The interactions of 232U(VI) with bentonite colloids ([U] = 5.43 x 10-­‐10 M; pH = 8.8 ± 0.2) have been studied using a resin ion exchange competition technique. The reversibility of the interaction was studied by allowing U(VI) to sorb to bentonite colloids for periods from 1 – 35 days. A fraction of the U(VI) was removed from the solution instantaneously (28-­‐50 %), and after 3 days, the amount of U(VI) remaining on the bentonite colloids was 17-­‐ 25%. With time, the amount of U(VI) retained by the bentonite colloid is reduced further, with a first order dissociation rate constant of 5.6 x 10-­‐7 s-­‐1. Whilst the dissociating fraction was small (24% (+34; -­‐12 %)), complete dissociation was not observed. Although slow dissociation was observed for U(VI), there was no convincing evidence for ‘irreversible binding’ of the radionuclide by the colloid. The interactions of 228Th(IV) ([Th] = 3.79 x 10-­‐12 M; pH = 8.8 ± 0.2) and 241Am(III) ([Am] = 3.27 x 10-­‐9 M; pH = 8.8 ± 0.2), with bentonite colloids have been studied using an ion exchange competition technique. Th(IV) was not fully associated with the bentonite colloids, and filtration showed that the uptake after 1 week was 78.3% (± 2.7%). Am(III) was weakly associated to the bentonite colloids, the uptake after 1 week was 20.1 % (± 5.2 %). Cellulose phosphate was added to the radionuclide/bentonite colloid systems (1 g for Th(IV), 0.2 g for Am(III)), an amount that was sufficient to retain the radionuclide when no bentonite colloids are present. A fraction of the Th(IV) is initially removed by the Cellphos (75-­‐93 %), and after 7 days the amount of Th(IV) remaining on the colloids is 1 -­‐ 3 %. Over the time of the experiment, the amount of Th(IV) retained by the bentonite colloid appears to remain level and the amount bound to the bentonite colloid at the end of the experiment is 2.1 % ± 0.88 % which is within experimental error of the steady state equilibrium of the system. A fraction (48-­‐94 %) of the Am(III) is also initially removed by the Cellphos, after 7 days the8amount of Am(III) remaining on the colloids is 1.2 – 9.3 %. However, after 35 days of contact time with the cellulose phosphate it appears that Am(III) is released back into the system, preventing dissociation rates from being calculated in this case. Studies of the association of Eu(III) to the clay colloids and its subsequent dissociation in this thesis follow similar trends to those described elsewhere in the literature (Missana et al. (2008), Bouby et al. (2011)). The Eu/bentonite colloid dissociation rate calculated here (8.8 x 10-­‐7 s-­‐1 (± 9.1 x 10-­‐7 s-­‐1)) is within error of the dissociation rates for trivalent ions estimated by Wold (2010) (Am(III) 5.6 x 10-­‐7 s-­‐1 Cm(III) 1.7 x 10-­‐6 s-­‐1). The U(VI) studies in this thesis show a dissociation rate of 5.6 x 10-­‐7 s-­‐1 (± 4.2 × 10-­‐7) which is within error of the U(VI) dissociation rate estimated by Wold (2010) (8.3 X 10-­‐7 s-­‐1). Reliable dissociation rates could not be obtained from the Am(III) and the Th(IV) studies in this thesis, other studies (e.g. Bouby et al. (2011) showed signs of irreversible binding of Th(IV) to bentonite colloids, however, no irreversible binding was observed in this thesis. Am(III) did not appear to be a close analogue of Eu(III) in these systems. All of the isotopes studied in this thesis showed no evidence of irreversible binding to bentonite or bentonite colloids. As such, the role that bentonite colloids will have in the facilitated transport of radioisotopes away from a repository is likely to have only a limited impact, at most, on the environmental safety case.

Yttria stabilized zirconia (YSZ) coatings were produced from a YSZ suspension in acetylacetone (ACAC) using electrophoretic deposition (EPD) and then consolidated via the natural drying and isothermal sintering with the constraint of the metal substrates. Before EPD, the operational pH of the suspension was adjusted by addition of acetic acid or organic bases. The effect of suspension pH on the deposition of EPD coatings was studied with respect to the suspension stability, coating density and microstructure both for a mono-sized system and micro-nano binary systems. The constrained drying process of the deposits was examined via the measurement of the critical cracking thickness (CCT). The sinterability of coatings was evaluated by micro-hardness and microstructure. For a mono-sized (0.26μm) suspension, results showed that the zeta potential had a high positive value on both sides of the isoelectric point (IEP). This probably resulted from the adsorption of base molecules triethanolamine (TEA), detected by fourier transform infrared spectroscopy. Three alkalis with different molecular structure were compared and the effect of their molecule length on the interparticle repulsion was discussed. Accordingly, the double layer thickness of the particles can be estimated. Based on this, particle interactions were estimated for different pH suspensions. The reduced particle coagulation increased the packing density of the EPD coatings from 38 % at pH 7.4 to 53 % at pH 8.4. Therefore, subsequent sintering of coatings was promoted. After sintering at 1200 °C, coatings made in pH 8.4 suspensions obtained a much higher hardness and had fewer big pores than coatings fabricated in pH 7.4 suspensions. The CCT of the latter is slightly higher than the former which might be ascribed to its particle network structure. In a binary suspension composed of the coarse (1μm) and fine (with average size of 100 nm or 10 nm, content varied in 0-30 wt. % to the powder mixture) YSZ powders, interactions between different species can be tuned by the zeta potential of individual component. Binary particles can be well dispersed at pH 4 when both of the coarse and fine powders reached their highest zeta potentials. Heterocoagulation occurred between them to form a haloing structure with fine powders covered on the coarse particle surfaces when they exhibited zeta potentials of the opposite sign at pH 8.6. Particle interactions were estimated and the microstructures of the binary coatings were examined to discuss how the different fine particle sizes influenced the particle packing after EPD. At pH 4, there existed a “stability window” for the 10 nm fines at 10 wt. % whereas no noticeable the border of the window can be observed for 100 nm fines within the measuring range. 10 nm and 100 nm fine powders gave similar overall densities of binary EPD coatings which were independent of the fine powder content. For heterocoagulation coatings made at pH 8.6, although the adsorption of fine particles reduce the agglomeration of coarse powder, the low zeta potential of the halos led to a loose structure of the “skeleton” ( the packing of the coarse powder) in the final binary coatings. 10 nm fine powders was observed to give a higher CCT and denser particle packing than 100 nm fine powders especially in a pre-saturated heterocoagulated binary coatings at 20 wt. % fine powder content. In order to further improve the sintering of the EPD coatings at low temperature sintering, a layer of CuO was applied on the coarse powder surface. With the addition of 30 wt. % fine powders, the hardness of EPD coatings after sintering 2 hours at 1150°C increased from 6 to 61 Vickers. With the presence of CuO, the hardness values were enhanced by 2.5-4.25 times. The density measurements indicated that the CuO layer not only served as a sintering aid, the CuO layer also helped with the binary particle packing particularly in the heterocoagulation condition because of the stronger particle interactions between the fine powders and CuO modified coarse powders. It seems that CuO had no significant impact on the cracking resistance of the binary coatings during drying, however t-m phase transformation was observed during sintering possibly due to the liquid phase induce by CuO.

SPIONs have unique material properties: ultra-small size and high magnetic susceptibility. These properties give SPIONs advantages to be used in a wide range of applications such as NMR/MRI contrast agents, cancer hyperthermia therapy, and cell- targeted and magnetically-triggered intracellular uptake. However, research has found that it is challenging to develop a SPION system that has controllable colloidal stability. This thesis endeavored to develop a SPION surface coating that allowed creation of a SPION system with known surface properties, hence enabling the study of its colloidal stability with a combination of computational and experimental methods. With the knowledge of colloidal behavior of nanoparticles, this thesis further explored the magnetic properties of SPIONs by designing lipid nanoparticles encapsulating (LNPs) that target and isolate a rare type of immune cell.

Removal of organic matter is increasingly important to drinking water utilities and consumers. Organic matter is a significant precursor in the formation of disinfection by-products (DBPs). The maximum contaminant levels for (DBPs) are decreasing and more DBPs are believed carcinogenic. Traditional coagulation focuses on the removal of particulate matter and in the last decade soluble species have also been targeted with high coagulant doses. However, colloidal matter is smaller than particulate matter and therefore not easily removed by conventional drinking water treatment. This research focused on the conversion of soluble organic matter to colloids using relatively low doses of ferric sulfate coagulant and the subsequent removal of the colloids by filtration during drinking water treatment. The goal is to achieve enhanced removal of soluble organic matter with minimal chemical costs and residual formation. This study investigated the effects of pH, iron coagulant dose, turbidity, organic matter concentration, and temperature on colloid formation. Characterization of the colloidal organic matter was attempted using zeta potential and sizing analyses. Cationic low molecular weight, nonionic high molecular weight, and cationic medium molecular weight polymers were evaluated on their removal of colloidal organic matter. Colloidal organic matter formation was affected by changes in coagulation pH, coagulant dose, and organic matter concentration, whereas turbidity and temperature did not significantly impact colloid formation. Decreased coagulation pH caused increased organic carbon removal. As coagulant dose was increased, colloid formation initially increased to maximum and subsequently rapidly decreased. Colloid formation was increased as the organic matter concentration increased. Due to low sample signal, the colloids could not be characterized using zeta potential and sizing analyses. In addition, polymers were ineffective for aggregating colloidal organic matter when used as flocculant aids. / Master of Science

This research evaluated natural organic matter (NOM) dissolved-solid phase separation resulting from alum coagulation under the following sourcewater conditions: pH, initial NOM concentration, initial turbidity, and temperature. The solid phase was partitioned into two operationally defined size fractions; colloidal matter was defined as organic carbon (OC) retained by a 30 kilodalton ultrafiltration membrane, and particulate matter was defined as OC retained by a 1μm glass-fiber filter. Coagulation pH had a considerable impact on residual OC colloid formation, signified by more colloids formed as a function of alum dose at pH 6.8 as compared to pH 5.8. Initial NOM concentration strongly influenced the alum dose range over which OC colloid formation occurred and was found to be a proportional relationship. The presence of bentonite clay (used as the initial turbidity source) somewhat affected OC colloid formation by exerting some amount of coagulant demand, signified by decreasing OC colloid formation with increasing initial turbidity. Coagulation temperature had a considerable impact on particulate matter formation, as there was an increase in the dose at which particle formation first occurred at 4 ºC when compared to 25 ºC. Phase separation of OC from dissolved to colloidal matter was very similar at both 4 ºC and 25 ºC. The ability for low doses of polymers to replace a large portion of alum in order to further aggregate colloids during flocculation was unsuccessfully investigated. OC phase separation resulting from alum and iron sulfate coagulation was compared on a molar coagulant metal basis. The amount of residual OC associated with colloidal matter was similar, while the critical coagulant dose at which particulate matter formed was shifted to a much higher dose for iron. / Master of Science

Depletion forces were used to separate an equinumber density binary dispersion of 1.5 and 0.82 µm polystyrene sulfate (PS) particles. Experiments consisted of injecting a pulse of a binary dispersion of PS particles into the inlet of a packed bed of 0.5 mm silica collector beads. Prior to injection, a carrier fluid of either KCl and KOH electrolyte or a silica nanoparticle dispersion was flowing through the column at steady state. When the carrier fluid was a dispersion of silica nanoparticles, the ratio of PS particles in the column outlet would change from 1:1 big to small particles to slightly over 2:1. This implies that more of the smaller 0.82 µm particles were being trapped on the surface of the collector beads due to depletion forces. Experiments with a single particle type (either 1.5 or 0.82 µm PS particle) were also done and correlated with the binary dispersion measurements. Potential energy profiles between a PS particle and a flat silica plate were calculated. The secondary energy barrier for the 1.5 µm particles was two times greater than for the 0.82 µm particles. Hence, the 0.82 µm particles were more likely to overcome the energy barrier and get trapped on the surface of the collector beads. Although the potential energy profiles were calculated at equilibrium, they can be used as a tool in finding the optimal conditions for separation. / Master of Science

Nos quadros de sepse ocorre o aumento da permeabilidade vascular, translocação e perda de albumina para o espaço extravascular, resultando assim em hipoalbuminemia e redução da pressão coloidosmótica plasmática. Desta forma o objetivo deste estudo foi avaliar a relação da pressão coloidosmótica com a evolução clínica de 41 cadelas com sepse grave ou choque séptico decorrente de piometra que foram submetidas a ovariosalpingohisterectomia. Para tanto, os valores da pressão arterial sistólica, do débito urinário, do lactato, do déficit de base venoso e da pressão coloidosmótica foram avaliados a cada três horas ao longo do período de internação. O momento da mensuração da pressão coloidosmótica foi distinto entre os grupos, sendo grupo I (critério clínico) (n= 21) avaliado após o fim do tratamento e no grupo II (critério quantitativo) (n= 20), as amostras foram avaliadas imediatamente após a colheita. As variáveis clínicas utilizadas como guia a administração de coloide no grupo I não apresentaram correlação com os valores de pressão coloidosmótica baixo. A administração de coloide não apresentou impacto sobre os valores de albumina e pressão coloidosmótica, bem como não interferiu na perfusão tecidual. A pressão coloidosmótica apresentou uma correlação não significativa e inversamente proporcional com o SOFA. Desta forma, a partir dos resultados obtidos é possível concluir que os valores da pressão coloidosmótica não apresentaram correlação com os valores das variáveis de perfusão tecidual; o coloide não contribuiu para a melhora da perfusão tecidual e da manutenção da pressão coloidosmótica após a administração de grandes volumes de solução cristaloide. / Sepsis induces increased vascular permeability, translocation and albumin loss to extracellular space, resulting in hypoalbuminemia and lower plasma colloid osmotic pressure. This study correlate colloid osmotic pressure with the clinical progress of 41 female dogs presenting severe sepsis or sepsis shock due to pyometra, submitted to ovario-salpingo-hysterectomy. The parameters evaluated were: systolic arterial pressure, urinary debt, blood lactate, venous base excess and colloid osmotic pressure. Samples were collected every three hours during the inpatient period. Laboratorial analysis of colloid osmotic pressure was performed in different timings: group I (clinic criteria, n=21), samples analyzed only after the end of the treatment; and group II (quantitative criteria, n=20): samples analyzed immediately after collection. The parameters were a guide to evaluate the necessity of colloid administration. We found no correlation between the parameters evaluate and the values of colloid osmotic pressure. The administration of colloid presented a non-significant and inversely proportional correlation with SOFA. We concluded that colloid osmotic pressure is not directly correlated with tissue perfusion and colloid administration does not improve tissue perfusion or colloid osmotic pressure, even after the administration of substantial volumes of crystalloid solution.