ABSTRACT AN INVESTIGATION OF THE MICROSTRUCTURAL AND MECHANICAL PROPERTIES OF TRI-CALCIUM PHOSPHATES DOPED WITH ALUMINUM AND FLUORIDE IONS Tahmasebifar, Aydin M. Sc., Department of Engineering Sciences Supervisor: Assoc. Prof. Dr. Zafer Evis August / 88 Pages The aim of this study was to investigate the microstructure and mechanical properties of pure tricalcium phosphate (TCP) and tricalcium phosphates doped with aluminum (Al3+) and fluoride (F-) ions at different compositions. TCP was synthesized via precipitation method and sintered at 1100

Arbetet syftar till att skapa en prototyp av en textil trycksensor som kan känna av och skilja på olika typer av belastning. En lämplig metod för att på ett vetenskapligt sätt testa sagda prototyp har också utvecklats. Prototypen har tillverkats för hand på en datoriserad vävstol och de ingående materialen är piezoelektrisk poly(vinyldifluorid), PVDF, tvinnad tillsammans med ett konduktivt garn, Shieldex®, samt polyester. När PVDF-fiber utsätts för töjning genererar de en spänning, vars storlek står i relation till töjningen. Den vävda konstruktion som valdes till prototypen är en distansvara där väftinläggen lagts in i 7 olika lager för att skapa volym. Därmed möjliggörs en töjning av PVDF-fibern som relaterar till trycket strukturen utsätts för. För att utvärdera strukturen skapades tre likadana trycksensorer innehållandes fyra PVDF-fiber som lagts in med ett mellanrum på ca 1,5 cm. Dessa prototyper har sedan fästs på en egentillverkad ramp och PVDF- samt Shieldex®-garnet har kopplats in till ett oscilloskop. Därefter har vikter rullats över prototypen för att generera spänning, vilken har kunnat uppmätas med oscilloskopet. De uppmätta resultaten har analyserats och utvärderats med hjälp av Excel. Testerna visade tydligt att spänningen som uppmättes stod i relation till vikternas storlek; högre vikter gav en mätbart större spänning. Det finns dock stor varians bland resultaten och utvärdering av samtliga prover visar på stora standardavvikelser hos samtliga fiber. Detta innebär att även om det är tydligt att ökad vikt medför ökad signal så kan det finnas svårigheter i att avgöra storleken på vikten utifrån den uppmätta spänningen. / The aim of this project was to create a sensor in textile material which can register and recognize different kinds of pressure. A suitable method has been developed in order to scientifically investigate and evaluate the sensitivity of the prototypes. The prototypes have been produced with a computerized hand weave machine and the materials used were polyester and piezoelectric PVDF-fiber, twisted with a conductive yarn, Shieldex®. When a force is applied to the PVDF-fiber, causing an extension of the fiber, a voltage is generated directly related to the applied force. The final prototype is a woven textile with integrated monofilaments and weft inserted in seven different layers to create a voluminous structure. An extension by the PVDF-fiber is there by enabled to occur which is related to the force applied onto the structure. Three equable prototypes were produced, each consisting four separated PVDF-fibers which were inserted with a distance of 1, 5 cm from each other. The prototypes were further attached one by one on a homemade ramp and the PVDF- and Shieldex®-fibers were connected to an oscilloscope. Different weights were then rolled from the top of the ramp, generating a voltage each time it pressures a fiber, which were seen on the computer software of the oscilloscope. The results were afterwards analyzed and evaluated using Excel. A clear relationship between applied force and generated voltage is shown although there is a great variety among the test results on each weight along with large standard deviations. The exact weight generating a specific voltage is therefore difficult to determine.

The main purpose of this research was to investigate new medical applications of femtosecond laser ablation. A near-infrared femtosecond laser was tested and proved to be able to overcome the existing limitations and outperform the conventional long-pulse lasers in the areas of human urinary calculus (kidney stone) lithotripsy and skin treatment. The two primary objectives of my research are: 1) to investigate the feasibility of using femtosecond pulsed laser radiation to ablate urinary calculus of various compositions. The laser-calculus interaction mechanism was characterized using pump probe imaging and fast flash imaging. A novel fiber delivery system was developed to transmit and focus high energy femtosecond pulses for urinary calculus lithotripsy. The successful demonstration of the femtosecond laser lithotripsy provided a promising treatment method better than the existing long-pulse laser lithotripsy in a few different aspects, including less collateral damage to surrounding tissue, small-size debris and more controlled experimental condition. 2) to investigate the depth limitation of femtosecond subsurface ablation in scattering skin sample and develop a prototype tissue optical clearing device to enhance femtosecond beam penetration for deeper subsurface cavitation production in the skin. The successful demonstration of the device has potential benefits to new femtosecond-based therapies for reshaping or removing subcutaneous tissues. / text

The design, synthesis and characterization of novel conjugated polymers are described. Using a coupling reaction recently developed within our labs, polymers were constructed through triazene linkages generated by joining N-heterocyclic carbenes (NHCs) with organic azides. This triazene reaction produced polymer of sufficiently high molecular weight as to be spin-coated and rendered conductive upon doping with iodine. The reaction also has potential for executing post-polymerization modifications. This was evidenced through rapid functionalization of poly(4-methylazido-styrene) via triazene formation using a commercially available N-heterocyclic carbene (NHC). A formal anion metathesis of benzobis(imidazolium)s was used to transform neutral block copolymers into block ionomers. Further investigation of the block ionomers revealed their solvent mediated self assembly. The gradual change of organic to aqueous media caused the adoption of a three-dimensional micelle conformation as determined by transmission electron microscopy and dynamic light scattering. Through the exploitation of carbene-carbon disulfide adducts, new chain transfer agents were generated. After 2-dithiocarboxylate-imidazolium adduct formation, alkylation was performed with benzyl bromide. The resulting charged chain transfer agent was tested for its ability to moderate radical addition fragmentation (RAFT) polymerizations of styrene. A considerable increase in transfer kinetics as compared to that of commonly used RAFT agents was observed whilst retaining low polydispersity and molecular weight control. The rate enhancement is presumably due to the electron withdrawing imidazolium activating the thionyl towards the nucleophilic radical while retaining effective fragmentation. Ion coordinating macrocycles were affixed to a poly(methacrylate) scaffold for employment as electrolyte extractants. Polymer bound calix[4]pyrrole was found to complex fluoride and chloride with sufficient strength as to extract tetrabutylammonium salts from water. Enhanced extraction abilities were observed when calix[4]pyrrole was used in conjunction with benzo-15-crown-5. Methacrylate polymers containing both macrocycles affected the removal of aqueous potassium fluoride from a biphasic water/dichloromethane mixture. To provide evidence for the presence of potassium fluoride within the dichloromethane layer, ¹⁹F NMR and flame emission spectroscopy were used. / text

The study of the binding and recognition of anions has emerged as a significant branch of supramolecular chemistry over the past 20 years. Of particular interest is the binding in aqueous media of industrially or biologically relevant anions including fluoride, pyrophosphate, and terephthalate. To date, most anion recognition using synthetic systems has been accomplished with small molecule receptors operating in organic media. We believe the challenge of sensing and binding anionic species in aqueous media could be addressed through polymers. This is due to their solubility, which can be tuned by judicious selection of the appropriate polymer backbone. Further, polymers can be cross-linked (forming interchain bonds) to produce insoluble materials that are attractive for use as filter materials for liquids and gases. The polymer network can also act as a net to strip away the solvent shell of the anions, leading to increased sensitivity toward hydrated analytes. In addition, the multi-valency due to multiple binding sites in a polymer can lead to increased affinities for analytes. This dissertation details the author’s work focused on the preparation of anion receptor-containing polymers and their subsequent evaluation as both sensors for the fluoride anion and as extractants for bisanions under conditions of liquid-liquid extraction. Chapter 1 gives a brief review of the challenges of anion binding and a primer on the field of sensing and extracting anions using polymeric systems. Chapter 2 describes our work incorporating three quinoxaline-based anion receptors into poly(methyl methacrylate) polymers and their sensing of anionic targets. Chapter 3 describes our work incorporating calix[4]pyrrole anion receptors into poly(methyl methacrylate) polymers. These polymeric systems were found to undergo reversible crosslinking in organic media when combined with certain ditopic anions. Chapter 4 describes our work to investigate chemopreventives of prostate cancer based on the phytochemicals 6-gingerol and 6-shogaol. The mechanism of action was linked to the inhibition of inflammation pathways. Derivatives of 6-shogaol were synthesized and their ability to inhibit prostate cancer cell growth was evaluated. Chapter 5 details all the syntheses and characterization data of the compounds discussed in this dissertation, as well as spectra from titrations and extraction studies. / text

published_or_final_version / abstract / toc / Dentistry / Doctoral / Doctor of Philosophy

Previous studies have shown that low-income Latinos frequently drink bottled water instead of tap water and might be at increased risk for dental caries from unfluoridated bottled water. The goals of this study were to: 1) determine if a difference exists between grab samples of municipal tap water and bottled water used by families in Nogales, Arizona in chemical and microbial contaminants; 2) understand the risk perceptions these low-income families have about both their publically supplied tap water, bottled/vended water; and 3) examine whether families have adequate fluoride levels in their drinking water for optimal dental health. Tap and bottled water samples were collected from thirty of these households for analysis of drinking-water contaminants regulated by the U.S. Environmental Protection Agency (USEPA). Bottled water included small (0.5 L) and large (3.8 L), individually sealed water bottles as well as water vended into reusable containers from self-service vending machines or from water stores. Some of the large bottles were purchased sealed, but had been previously opened and partially consumed by study participants. In addition to the 30 households mentioned above, an additional sixty low-income Latino households, who primarily drink bottled water, were also recruited for this study to complete a questionnaire on risk perceptions related to drinking water consumption, water storage practices, and fluoride supplementation. There were no significant differences in the concentration of chemical contaminants between tap, bottled and vended water, and none of the chemical concentrations exceeded USEPA regulations. Escherichia coli (E. coli) was confirmed in 3% (1/30) of tap, 0% (0/8) of sealed bottled, 40% (2/5) of previously opened bottled, and 35% (6/17) of vended water samples. One of the 3 samples collected directly from a vending machine had an E. coli concentration of 0.33 CFU/100 mL. None of the 10 samples collected directly from sealed bottles purchased directly from the store had any E. coli detected. While no significant differences were observed in the chemical quality of water samples, results suggest that secondary contamination in the home contributes to higher levels of E.coli in water from partially consumed larger water bottles or water stored in reusable containers. Families who reported cleaning large reusable water containers with soap or hot water had significantly lower E.coli (p=0.003) in their drinking water than those who rinsed with only water. Respondents viewed bottled water to be significantly safer to consume than tap water (p<0.001). On a Likert scale from 1 (low risk) to 5 (high risk), "drinking tap water in Nogales, Arizona" received an average score of 4.7, which was significantly higher than the average perceived risk of smoking (µ= 3.5, p<0.001) or of "drinking tap water in San Francisco, California" (µ= 3.4, p<0.001), and as risky as "drinking and driving" (µ= 4.8, p=1.00) and "drinking tap water in Nogales, Sonora, Mexico" (µ= 4.8, p=1.00). Additionally, 98% (88/90) of respondents feared that drinking local tap water could result in illness. The majority of respondents (79%, 71/90) did not drink their tap water because of fear of contamination and would drink their tap water if they knew it was safe, regardless of the taste (73%, 66/90).Fluoride was detected in 53% (16/30) of tap-water samples and only in one bottled-water sample. However, only 27% (8/30) of tap-water samples had fluoride levels within the recommended range (0.7-1.2 mg/L) by the American Dental Association for optimally fluoridated water. From multiple logistic regression, children in a household were less likely to have cavities if their parents reported using fluoridated mouthwash (p<0.001) or visited the dentist yearly (p<0.001). None of the participants reported discussing the type of water they drank or fluoride supplementation with any healthcare providers. Results suggest that secondary contamination in the home is contributing to significantly higher levels of bacteria in vended water stored in reusable containers. In addition, fear of illness from contamination of tap water is an important contributing factor to increased use of bottled water. Interventions could be developed to educate families about how to keep their reusable water containers clean, reduce perceived risks associated with tap-water consumption, and emphasize the importance of fluoride supplementation if families continue drinking bottled water.

Fluoride based chemical systems are widely used at various stages in microelectronic processing, particularly for wet cleaning and etching applications. Some examples include the use of semi aqueous fluoride (SAF) solutions in back end of line cleaning, the use of dilute HF solutions as etchants for SiO2 and HF-HNO3 or HF-H2O2 solutions as isotropic etchants for silicon. In this work, the use of fluoride based solutions for two applications relevant to semiconductor processing are considered.In the first part of the study, cleaning of post plasma etch residues generated during fabrication of copper damascene structures was investigated in semi aqueous fluoride (SAF) formulations based on dimethyl sulfoxide and ammonium fluoride. Formulations designed for residue removal should be able to remove the residue effectively, without causing critical dimension loss during the process cycle. A systematic evaluation of solution variables (solvent content and pH) was conducted and the extent of removal of model copper oxide films and selectivity over copper and carbon doped oxide (CDO) films were used as metrics to evaluate the formulations. Results of the study indicate that the presence of solvent is necessary to achieve reasonable etch selectivity over dielectric films. Additionally, a removal end point detection technique based on electrochemical impedance spectroscopy was developed, which could potentially help in the optimization of cleaning time with minimal dielectric loss. This method was applied to monitor the removal of copper oxide films as well as residue from patterned test structures.In the second part of the study, electrochemical formation of porous silicon films in hydrofluoric acid (HF) solutions was investigated, for potential applications in advanced packaging. Specifically, porous silicon formation in solution mixtures containing HF, acetic acid and peroxide, was studied. The effect of variables including current density, substrate resistivity, HF, acetic acid and peroxide concentration, on key porous film characteristics such as growth rate, porosity and microstructure, was explored. Addition of peroxide was found to significantly increase the porosity and growth rate of the film, as a result of enhanced chemical dissolution and films with porosities as high as 95% were obtained. Additionally, in solutions containing peroxide, a variety of microstructural features, such as nanopores, micron sized pores, truncated pyramidal structures and silicon needles were observed, under various fabrication conditions.

The present work is to study slag phenomena in steelmaking process. In order to attain thegoal, a number of high temperature experiments and simulation experiments were carried out. Four master slags were used to study the effect of CaF2 on slag viscosity. Experimentalresults indicated the effect of CaF2 on slag viscosity depended strongly on the composition ofmaster slag. For high basicity slags, CaF2 mainly suppressed the precipitation of solid phasesat lower temperatures, leading to a lower viscosity compared to CaF2-free slags. For slagswith higher SiO2 contents, CaF2 both lowered the viscosity of the liquid phase and suppressedthe precipitation of solid phases. The viscosities of solid-liquid mixtures were experimentally determined for silicon oilparaffinsystem at room temperature and solid-liquid oxide mixture at steelmakingtemperature. The results of both measurements indicated that the increasing trend of mixturesviscosity with particle fraction can be described by Einstein-Roscoe equation.Silicone oils of different viscosities were used to simulate slag foaming. The experimentalresults showed, at a constant viscosity, the foaming height increased first with superficialvelocity before reaching a maximum value. Thereafter, the foaming height decreased with thefurther increase of the superficial velocity. Similar, a maximum foaming height was observedat an optimum viscosity when a constant superficial gas velocity was applied. Based on theexperimental data, a semi-empirical equation of foaming height was developed. Thepredictions of the model agreed well with experiment data. The model could also reasonablywell explain the industrial pilot trial experiments. Water-silicon oils model and liquid alloy (Ga-In-Sn)- 12% HCl acid model were employed tosimulate the formation of open-eyes in a gas stirred ladle. The experimental results indicatedthat the viscosity of the top liquid and the interfacial tension between the two liquids had onlylittle effect on the open-eye size. A semi-empirical model was developed to describe the sizeof open-eye as functions of the gas flow rate, bath height and slag height. The two sets ofparameters obtained for the water and Ga-In-Sn models were very different. Industrial trialswere also conducted to examine the applicability of the models. Liquid alloy model couldwell predict the formation of an open-eye during ladle treatment. Two cold models, sodium tungstate-oil model and water-oil model, were carried out tosimulate the formation of droplets in a gas stirred ladle. The experimental results showed thatthe gas flow rate and interfacial tension had strong impact on the size of droplets. A semiempiricalmodel was developed to describe the size of droplets for water model. Meanwhile,the parameter obtained for water model can be used for sodium tungstate-silicone oil system.The results indicate the model has strong compatibility. / QC 20110419

A new class of polymer coated lanthanide fluoride nanoparticle aggregates (NPAs) was developed as potential MRI contrast agents. The NPA synthesis has been perfected to control the size distribution and optimize relaxivities. Polyacrylic acid was used as a stabilizing polymer, and was conjugated to folic acid to improve targeting to SK-BR-3 breast cancer cells. Terbium was incorporated in the synthesis to study the passive and active targeting properties of NPAs. Through a series of microscopy experiments, a significant difference in uptake between NPAs with and without targeting moieties occurs after 48 hours of incubation. The relaxivity of the optimized nanoparticles was measured to be 56 s-1(mg/ml)-1 using a 1.5 T scanner, which may be compared to that of the commercially available Gd3+-DTPA [R1 = 7 s-1(mg/ml)-1]. Abdominal perfusion studies in rats also demonstrated that the NPAs provide better contrast of the vasculature than Gd3+-DTPA does at the same mass concentration.