No description available.

Polychlorinated Biphenyls (PCBs) are a group of 209 congeners that are regulated under the Toxic Substance Control Act. They enter the environment as a result of industrial processes and can travel long distances. PCBs are environmentally persistent and bioaccumulate in animal populations. Painted surfaces are a common point source for PCBs and there are few options for remediating structures painted with PCB-contaminated paint. Removal of the paint can often spread contamination and disposing or burning of large structures is expensive. Experiments employing reductive dehalogenation through the use of a bimetal have shown that PCBs can be degraded in mild laboratory conditions. This dissertation describes the process of developing an application media that will enable the degradation process reported in literature to be used in a field application. An environmentally friendly reaction environment had to be established as well as the treatment‟s operating parameters. In collaboration with researchers at the National Aeronautics Space Administration (NASA), Kenney Space Center (KSC), researchers at the University of Central Florida (UCF) developed a bimetallic treatment system (BTS) that can remove and degrade PCBs from painted surfaces. The technology was evaluated during a field demonstration at a decommissioned Department of Defense facility in Badger, Wisconsin. Samples of treatment paste, paint and concrete were analyzed over a three week period. The PCB concentrations in both the paint and concrete dropped dramatically as a result of the demonstration, and in many instances, were lowered below the EPA action limit of 50ppm. In the laboratory, additional studies were conducted to further the degradation in the treatment system. Through this process, a novel degradation system was established containing zero-valent magnesium and ethanol acidified with acetic acid. The use of acidified ethanol permitted the degradation to occur with iv just magnesium powder and eliminated the use of a bimetal and therefore palladium. The technology was incorporated into a modified treatment system termed Activate Metal Treatment System (AMTS). The AMTS was used on samples from a second field site where paint chips from an manufacturing warehouse in New York state were degraded to thousands of mg/kg (ppm) below their starting concentrations.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Transformation of amorphous calcium phosphate (ACP) and brushite into hydroxylapatite, an important biomineral, has been documented. The relationships between synthesis conditions and the formation and transformation of these phases are not comprehensively understood. The metastable nature of ACP has made it historically challenging to investigate, and many analyses attempt to stabilize the phase through drying or including additional ions or proteins in the reaction. In situ investigations provide an incisive approach to examining the structure and transformation of ACP and brushite as a function of synthesis conditions. The first project develops a new method for in situ analyses of the structure of ACP and brushite shortly after reagent mixing, without chemical stabilization. This method was used in the second project to examine how the initial Ca/P affects ACP structure and transformation. Our results identify the first structural differences in types of ACP, controlled by the initial Ca/P. At ratio 0.2 the Ca – P bonding geometry is primarily monodentate, ratio 5.0 produces a coordination that is primarily bidentate, and there is a mix of monodentate and bidentate coordinates at intermediate ratios between the two. These results are independent of system pH between the examined range of 6-11. Further ex situ transformation experiments identified that at ratio 0.2, ACP transformed directly into hydroxylapatite, but at higher ratios the transformation product is brushite. This is a promising mechanism for direct ACP to hydroxylapatite conversion at a biologically relevant pH. In the final project, the statistically significant synthesis parameters (age, pH, temperature, supersaturation, and initial ion ratio) for ACP, brushite, and hydroxylapatite formation are evaluated. Binary logistic regression analysis and nonlinear continuous logistic regression analysis are applied to a dataset compiled from the literature. Equations were developed that predict the percentage of ACP and brushite that will form. The equations and significant variables seem to depend on the transformation pathway of brushite and ACP. The current analysis did not comprehensively describe hydroxylapatite formation when trying to concurrently evaluate the ACP to hydroxylapatite and brushite to hydroxylapatite pathways. Taken together, these studies provide new ways to study and interpret calcium phosphate phases as they form and transform. Experiments identified new relationships between the chemistry and structure of ACP. The new in situ experimental method and the equations we developed can be used to improve future experimental designs towards a comprehensive understanding of the calcium phosphate system. / Doctor of Philosophy / Hydroxylapatite is a mineral made of calcium and phosphate, that is similar to the mineral components of bones and teeth in humans and other mammals and fish. Hydroxylapatite and other calcium phosphate phases can form when solutions, rich in calcium and phosphate, are mixed. Phases without long-range crystal structure, are amorphous calcium phosphates (ACP). Additional calcium phosphate minerals, like brushite can also form. If brushite and ACP are left in solution, they will transform into hydroxylapatite over time. Major questions include the need to learn the short-range atomic structure of ACP and how ACP and brushite transform into hydroxylapatite In this dissertation, I investigate how chemistry and other variables such as age and time impact the calcium phosphate phase to form and how it transforms with aging. The first project develops a new method to study the structure of ACP and brushite without drying the study materials or adding additional chemicals or proteins to prevent them from transforming. The sample forms in a solution and flows directly through an X-ray beam for structural analysis. This method is used in project two to examine how the ratio of calcium and phosphate in the beginning of the reaction affected the structure of ACP and how it transformed. The results identify the first structural differences in types of ACP, controlled by the initial Ca/P. At a ratio of 0.2 a calcium and phosphorus atom mostly share only one oxygen between them, but at Ca/P = 5.0, they mostly share two oxygens. At ratios in between 0.2 and 5.0 they share a mix of one and two oxygens. The results are independent of pH. Additionally, at ratio 0.2, ACP transformed directly into hydroxylapatite, but at all other ratios it transformed to brushite. Investigations of direct ACP to hydroxylapatite transformation are usually performed at a pH above that found in humans, but the transformation at low ratio occurred at a biologically relevant pH. In the final project statistical analysis was used to identify what synthesis conditions (out of age, pH, temperature, supersaturation, and initial ion ratio) had a significant impact on the formation of ACP, brushite, and hydroxylapatite. Equations were developed that can be used to predict the percentage of ACP and brushite that form based on the statistically significant variables. The current analysis did not fully describe hydroxylapatite formation. Results suggest separate equations are needed for hydroxylapatite forming directly from ACP and directly from brushite. Combined, these studies have created new ways to study calcium phosphate phases as they form and transform. This work experimentally identified new relationships between the chemistry and structure of ACP. Both the method and equations will help researchers improve their future experimental designs so investigations can be more directly compared to create a comprehensive understanding of calcium phosphates.

Diese wissenschaftliche Arbeit beschäftigt sich mit der Messung des Gehalts bauschädlicher Salze in porösen Baustoffen mit Hilfe der Röntgenfluoreszenzanalyse. Die Analyse des Salzgehalts ist von besonderer Bedeutung, um historische Gebäude zu erhalten und Schäden durch Feuchtigkeit und Salze zu vermeiden. Derzeit genutzte Laboranalysen sind jedoch kostspielig und zeitaufwendig, daher ist eine Möglichkeit der zerstörungsfreien In-situ Analyse wie die Röntgenfluoreszenzanalyse, sehr gefragt. Das Ziel dieser Arbeit besteht darin, herauszufinden, ob die Röntgenfluoreszenzanalyse geeignet ist den Gehalt an bauschädlichen Salzen in porösen Baustoffen zu bestimmen. Zu diesem Zweck wurden insgesamt 32 Ziegelproben mit unterschiedlichen Konzentrationen von Natriumchlorid und Natriumsulfat belastet und verschiedenen Lagerungsbedingungen ausgesetzt. Durch die Untersuchung unterschiedlich präparierter Probengruppen sollten mögliche Einflüsse auf das Messsignal erforscht werden. Die Ergebnisse der Untersuchungen zeigten, dass Feuchtigkeit das Messsignal erheblich abschwächen kann. Dennoch verhalten sich die Ergebnisse zur Salzkonzentration in allen Probengruppen proportional zur steigenden Zielbelastung. Darüber hinaus lassen sich die Ergebnisse mit denen der, als Referenz durchgeführten, Photometer Analyse vergleichen.:Kurzfassung Abstract Inhaltsverzeichnis Abbildungsverzeichnis Tabellenverzeichnis Abkürzungsverzeichnis 1 Einleitung 1.1 Zielsetzung und Problemstellung 1.2 Stand der Technik und der Wissenschaft 1.3 Salzarten und ihr Vorkommen 1.4 Ursachen und Schadwirkung von bauschädlichen Salzen 2 Verfahren zum Analysieren von Salzen 2.1 Halbquantitative Analyse mit Teststäbchen 2.2 Quantitative Analyse mit Photometer 2.3 Röntgenfluoreszenzanalyse 3 Durchführung 3.1 Vorbetrachtung 3.2 Herstellung und Prüfung der Proben 3.3 Belastung und Lagerung der Proben 3.4 Alternative Salzanalyse mit dem Photometer 3.5 Messaufbau und Eigenschaften der RFA 4 Darstellung der Ergebnisse 4.1 Analyse der unbelasteten Proben 4.2 Analyse der mit Leitungswasser belasteten Proben 4.3 Analyse der mit Natriumchlorid belasteten Proben 4.4 Analyse der mit Natriumsulfat belasteten Proben 4.5 Weitere Ergebnisse der RFA 4 5 Auswertung der Ergebnisse 5.1 Interpretation 5.2 Vergleich mit dem Stand der Technik 5.3 Einschränkungen und weitere Forschung 6 Zusammenfassung und Fazit Weitere Bilder Literaturverzeichnis Eidesstattliche Erklärung / This scientific work deals with the measurement of the content of building-damaging salts in porous building materials using X-ray fluorescence analysis. The analysis of the salt content is of particular importance to preserve historic buildings and prevent damage caused by moisture and salts. However, currently used laboratory analyses are costly and time-consuming, so a possibility of non-destructive in-situ analysis, such as X-ray fluorescence analysis, is in great demand. The aim of this work is to find out whether X-ray fluorescence analysis is suitable for determining the content of building-damaging salts in porous building materials. For this purpose, a total of 32 brick samples were loaded with different concentrations of sodium chloride and sodium sulphate and exposed to different storage conditions. By examining differently prepared groups of samples, possible influences on the measurement signal were to be investigated. The results of the investigations showed that moisture can considerably weaken the measurement signal. Nevertheless, the results for the salt concentration in all sample groups are proportional to the increasing target load. Furthermore, the results can be compared with those of the photometer analysis carried out as a reference.:Kurzfassung Abstract Inhaltsverzeichnis Abbildungsverzeichnis Tabellenverzeichnis Abkürzungsverzeichnis 1 Einleitung 1.1 Zielsetzung und Problemstellung 1.2 Stand der Technik und der Wissenschaft 1.3 Salzarten und ihr Vorkommen 1.4 Ursachen und Schadwirkung von bauschädlichen Salzen 2 Verfahren zum Analysieren von Salzen 2.1 Halbquantitative Analyse mit Teststäbchen 2.2 Quantitative Analyse mit Photometer 2.3 Röntgenfluoreszenzanalyse 3 Durchführung 3.1 Vorbetrachtung 3.2 Herstellung und Prüfung der Proben 3.3 Belastung und Lagerung der Proben 3.4 Alternative Salzanalyse mit dem Photometer 3.5 Messaufbau und Eigenschaften der RFA 4 Darstellung der Ergebnisse 4.1 Analyse der unbelasteten Proben 4.2 Analyse der mit Leitungswasser belasteten Proben 4.3 Analyse der mit Natriumchlorid belasteten Proben 4.4 Analyse der mit Natriumsulfat belasteten Proben 4.5 Weitere Ergebnisse der RFA 4 5 Auswertung der Ergebnisse 5.1 Interpretation 5.2 Vergleich mit dem Stand der Technik 5.3 Einschränkungen und weitere Forschung 6 Zusammenfassung und Fazit Weitere Bilder Literaturverzeichnis Eidesstattliche Erklärung

No description available.

No description available.

Mitochondria are intracellular organelles responsible for oxidative phosphorylation. They contain their own DNA which encodes some components involved in oxidative phosphorylation. Mitochondrial DNA is very susceptible to mutations. Mitochondrial abnormalities have been observed in several disorders of muscle and brain. Alzheimer's disease is a form of dementia characterized by the formation of numerous neuritic plaques and neurofibrillary tangles. There is evidence suggesting a possible role for mitochondrial abnormalities in Alzheimer's disease. The goal of this project was to determine if there were quantitative changes in mitochondrial DNA content in large neurons from Alzheimer's disease patients, compared to age-matched control patients. The relative mitochondrial DNA content per unit area was assessed in brain sections from Alzheimer's disease subjects and age-matched control subjects using in situ hybridization to mitochondrial DNA. The results were not conclusive due to technical concerns with the in situ hybridization technique which are discussed. / Thesis / Master of Science (MS)

Una de las características más importantes del polipropileno (PP) es su versatilidad, la que hace posible, por ejemplo, su modificación mediante distintos métodos físicos y químicos ampliando su rango de aplicaciones. Entre las modificaciones que se le pueden hacer al PP se encuentra el mezclado con cargas, y en particular con nano-cargas, las que tienen al menos una dimensión en escala nanométrica. Las arcillas, y sobre todo, la montmorillonita (MMT), son una de las nano-cargas más usadas para la preparación de nanocompuestos de PP, aun cuando deben ser tratadas para darles un carácter organofílico (o-MMT). El método más usado hasta el momento para generar las mezclas de PP y o-MMT es el mezclado en fundido ya que es un proceso pos-reactor que resulta fácil de implementar con equipamiento de procesamiento habitual. Sin embargo, la aplicación de este método suele requerir el uso de un agente compatibilizante con cierto grado de polaridad, como es el PP modificado con anhídrido maleico. Los avances logrados en la preparación de nanocompuestos de PP y o-MMT han sido muchos desde que se comenzaron a estudiar hace un par de décadas. Sin embargo, los materiales que se han obtenido usando mezclado en fundido con compatibilizantes no presentan el nivel de mejora en sus propiedades que se observan en otros nanocompuestos poliméricos. Una técnica similar, aun casi no explorada y de fácil implementación a nivel industrial, es aquella que no utiliza compatibilizante sino que trata de generarlo in-situ, durante el mezclado, mediante la modificación química del polímero. Se plantea así el objetivo de esta tesis, que es obtener nanocompuestos basados en PP y MMT por mezclado reactivo en fundido, con buen grado de desagregación y exfoliación de las partículas de arcilla de manera de mejorar propiedades físicas del PP. Durante el desarrollo del trabajo se ha explorado el efecto del funcionalizante durante el procesamiento reactivo con intención de generar el compatibilizante in-situ, se han analizado distintas políticas de incorporación de componentes al medio de reacción, y se han evaluado las propiedades de flujo, térmicas y de barrera de los materiales obtenidos en función de sus características estructurales, concentración de componentes y procedimiento de mezclado. Los resultados obtenidos muestran que: es posible obtener nanocompuestos de PP y arcilla por funcionalización in-situ usando tanto anhídrido maleico (AM) como acrilato de n-butilo (BA). Se ha encontrado, además, que el mezclado secuencial, en el que se funde el PP y se agrega la arcilla a mitad del tiempo total de procesamiento durante el mezclado reactivo, es el procedimiento que genera mayor intercalación y/o grado de exfoliación de la arcilla tanto al usar AM como BA. Este mecanismo produce materiales en los que la permeabilidad al oxígeno y la velocidad de degradación oxidativa del PP son disminuidas significativamente sin afectar de manera notable la transparencia del polímero o sus procesos de cristalización y fusión. Además, la disminución del peso molecular de la matriz polimérica hace que las propiedades de flujo de los compuestos obtenidos no superen las del PP, lo que es otra consecuencia beneficiosa desde el punto de vista tecnológico. / One of the most important features of polypropylene (PP) is its versatility, which makes it possible, for example, the modification using different physical and chemical methods increasing its range of applications. Among the modifications that can be made to PP, one is the mixing with fillers, and particularly, with nano-fillers, which have at least one dimension in the nanoscale. The clays, and especially montmorillonite (MMT), are one of the nano-fillers more used in preparing nanocomposites of PP, even though they must be treated to give them organophilic characteristics (o-MMT). The method most used so far to produce the mixing of PP and o-MMT is melt mixing, since it is a post-reactor process that may be easily implemented with standard processing equipment. The application of this method generally requires the use of a compatibilizing agent with some degree of polarity, such as maleic anhydride grafted PP (PPgA). In the last decades there have been many advances in the preparation of compatibilized nanocomposites of PP and o-MMT using melt mixing. However, the materials that have been obtained so far using this methodology do not show the level of improvement in properties that have been observed in other polymeric nanocomposites. A similar technique, still almost unexplored and that can be easily implemented on an industrial level, is the one that does not use a compatibilizer but rather generates it in-situ during mixing by chemical modification of the polymer. This raises the goal of this thesis, which is to obtain nanocomposites based on PP and MMT using reactive melt mixing, with good degree of delamination and disintegration of the clay particles in order to achieve improved physical properties. During the development of the work, the effect of the functionalization of the polymer during the reactive processing has been explored trying to generate the compatibilizer in-situ. Also, different policies of incorporating components to the reaction medium have been considered, and the flow, thermal and barrier properties of the obtained materials have been evaluated as a function of the structural characteristics of the composites, the concentration of the components, and the type of mixing process. The obtained results show that: it is possible to obtain nanocomposites of PP and MMT using in-situ functionalization with both, maleic anhydride (AM) and n-butyl acrylate (BA). It has been found also that the sequential mixing, which begins by melting the PP and contemplates the addition of the clay half the way during the reactive mixing, is the procedure that generates the greater intercalation and/or the largest degree of exfoliation of the clay, both with AM and BA. This mechanism produces materials that display oxygen permeability and oxidative degradation rate that are significantly smaller than in PP without affecting considerably the transparency of the original polymer and its crystallization and melting processes. Moreover, the reduction of the molecular weight of the polymeric matrix makes that the flow properties of the obtained compounds are smaller than those of the original PP, which is another beneficial result from the technological point of view.

The objective of this study was to determine if the method of incorporation of a silicate layered nanoclay into a polymer matrix can affect the barrier properties of the pristine polymer in order to decrease the transport of volatile organic compounds (VOC) in indoor air. Building materials are a primary source for VOCs. These emissions are a probable cause of acute health effects and discomfort among occupants and are known to diminish productivity. The predicted concentrations of several of the VOCs emitted by structural insulated panels (SIP) are of concern with respect to health and comfort of occupants. The main issue related to the barrier membranes is the dispersion properties of the nanoclays in the polymer matrix, and the generation of a tortuous pathway that will decrease gas permeation. The tortuous pathway is created by a nanoclay filler, whose ideal exfoliated structure has high surface area, and high aspect ratio. By choosing the appropriate surfactants, the nanoclays can be modified to allow improved molecular interactions between the nanoclay and the polymer matrix. Several studies were performed in order to evaluate the dispersion properties of the nanoclay in the polymer matrix. Polymer/clay nanocomposites barrier membranes were generated via different synthesis methods. In the first study, barrier membranes were composed of a polyurethane, Estane ® 58315, and different nanoclays, Cloisite ® 10A, Cloisite ® 20A, Cloisite ® 30B. The interaction of the polyurethane and the different surfactants used to organically modify the nanoclay was evaluated. The dispersion of the clay platelets was analyzed by varying the pre-processing method; sonication vs stirring. The decrease in gas permeability results was enhanced by the effect of pre-processing via sonciation in comparison to plain stirring. These results also suggest that nanoclay platelets modified with alkylammonium groups with one tallow tail Cloisite ® 10A and Cloisite ® 30B, allow better dispersion and penetration of the polymer within the basal spacing of the nanoclays. Once the decrease in gas permeability was confirmed, the next challenge was to study and evaluate the performance of the polyurethane/clay nanocomposites barrier membranes in the determination of diffusivity coefficients for volatile organic compounds (VOCs). This was achieved via gravimetric sorption characterization. This method allowed for characterization of the sorption and desorption phenomena of VOC in barrier membranes. Barrier membranes pretreated with sonication demonstrated lower diffusivity coefficients than those only treated with stirring. At high clay loadings, 50 wt% of nanoclay in the polymer, the decrease in diffusivity coefficients for VOCs such as butanol and toluene, was found to be one order of magnitude. Other VOCs such as decane and tetradecane also showed a significant decrease in diffusivity coefficient. The results for VOC sorption studies suggest that there is some variability. In order to enhance the exfoliation of the clay, we decided to examine in situ polymerization of poly (n-butyl methacrylate) in the presence of nanoclay. In this study the clay wt% was kept at a low concentration of 1-5 wt%. The surface modification of natural montmorillonite, Cloisite ® Na+, was achieved via ion exchange, and the effect of pre-processing was also explored. The modification rendered a tethered group on the surface of the clay that was able to react with the monomer/oligomer chains and thus expand and exfoliate the clay platelets. Gas permeation data suggest that sonication also produced better barrier properties than its counterpart stirring. XRD diffractograms also confirmed exfoliation of the clay platelets in the poly (n-butyl methacrylate) polymer matrix. Thermogravimetric analysis (TGA) suggested that exfoliation of the clay platelets led to improved thermal stability by increasing the decomposition temperature of the membranes. A small increase in Tg also suggested restricted segmental chain motion within the clay platelets. Overall gas permeation decreased even at low clay content. Phenomenological models such as those of Cussler and Nielsen were used to model the experimental permeation results. These models suggest that although the aspect ratio of the clay platelets is within the specifications provided by the manufacturer, it does not reflect the ideal behavior of the models. The last step of this work was to achieve exfoliation of the modified nanoclay platelets via emulsion polymerization of poly (n-butyl methacrylate). The clay concentration in the emulsion was kept the same as in the in situ polymerization. DLS results suggest a uniform distribution of the polymer/clay nanocomposites particles in the emulsion. Permeation data indicated higher permeation values than the in situ method of synthesis of the nanocomposite membranes. This led us to explore the use of glassy co-polymer of poly(n-butyl methacrylate)-poly(methyl methacrylate) as the matrix. The addition of a more glassy component in the polymer matrix led to improved barrier properties of the nanocomposite membranes. As expected, the copolymer had a higher Tg than the PMMA polymer. Analysis via phenomenological models, also suggested that the chemistry of the co-polymer played an important role in decreasing gas permeability within the polymer/clay nanocomposite membranes, although the effect of the glassy component in the matrix was not quantified by the phenomenological models. / Ph. D.