Biomarkers present a non-invasive means of detecting cancer because they can be obtained from body fluids. They can also be used for prognosis and assessing response to treatment. To limit interferences it is essential to pretreat biological samples before analysis. Sample preparation methods include extraction of analyte from an unsuitable matrix, purification, concentration or dilution and labeling. The many advantages offered by microfluidics include portability, speed, automation and integration. Because of the difficulties encountered in integrating this step in microfluidic devices most sample preparation methods are often carried out off-chip. In the fabrication of micro-total analysis systems it is important that all steps be integrated in a single platform. To fabricate polymeric microdevices, I prepared templates from silicon wafers by the process of photolithography. The design on the template was transferred to a polymer piece by hot embossing, and a complete device was formed by bonding the imprinted piece with a cover plate. I prepared affinity columns in these devices and used them for protein extraction. The affinity monolith was prepared from reactive monomers to facilitate immobilization of antibodies. Extraction and concentration of biomarkers on this column showed specificity to the target molecule. This shows that biomarkers could be extracted, purified and concentrated with the use of microfluidic affinity columns.I prepared negatively charged ion-permeable membranes in poly(methyl methacrylate) microchips by in situ polymerization just beyond the injection intersection. Cancer marker proteins were electrophoretically concentrated at the intersection by exclusion from this membrane on the basis of both size and charge, prior to microchip capillary electrophoresis. I optimized separation conditions to achieve baseline separation of the proteins. Band broadening and peak tailing were limited by controlling the preconcentration time. Under my optimized conditions a 40-fold enrichment of bovine serum albumin was achieved with 4 min of preconcentration while >10-fold enrichment was obtained for cancer biomarker proteins with just 1 min of preconcentration. I have also demonstrated that the processes of sample enrichment, on-chip fluorescence labeling and purification could be automated in a single voltage-driven platform. This required the preparation of a reversed-phase monolithic column, polymerized from butyl methacrylate monomers, in cyclic olefin copolymer microdevices. Samples enriched through solid phase extraction were labeled on the column, and much of the unreacted dye was rinsed off before elution. The retention and elution characteristics of fluorophores, amino acids and proteins on these columns were investigated. A linear relationship between eluted peak areas and protein concentration demonstrated that this technique could be used to quantify on-chip labeled samples. This approach could also be used to simultaneously concentrate, label and separate multiple proteins.

The purpose of the study was to identify the basis of the aspiring principal preparation program (appp) components florida school districts provide to their aspiring principals and their relationship, if any, to the state and isllc standards. A total of 50 school districts in florida participated in this study. The research was guided by the following questions: to what extent do the florida school districts provide a formal appp to their current assistant principals? (b) upon what are the formal appps for current assistant principals based: the florida principal competencies (fpcs), the interstate school leaders licensure consortium (isllc) standards, or another source? (c) to what extent do the school district appps in the 67 florida districts have component requirements that include professional development, mentoring, and a performance-based experience? and (d) are there differences among the appp components provided by florida school districts of various sizes? the findings of the study were found through an examination of quantitative and qualitative data that were collected from the florida aspiring principal program assessment (flappa) survey and the school districts' appp brochures located on their websites. This study supported the following conclusions: (a) 75% of the school districts in florida do provide an appp for their aspiring principals, (b) the fpcs and the isllc standards are a part of the bases of the components found in appps provided by florida school districts, (c) florida school districts do provide appps that include components of a mentor principal, a performance-based experience, and professional development, (d) very large-sized school districts with a population over 100 thousand students contained the largest percentage of standards-based components in the appp; small-sized school districts with a population of under 7 thousand students contained the least percentage of standards-based components in the appp, (e) school districts in florida recognized the need to modify and were in the process of modifying their appps according to the new florida leadership standards, especially the component of technology, and (f) a lack of funding, time, and assessment were identified as appp weaknesses and components in need of improvement. Recommendations of this study included: (a) further research on florida school districts redesign of their appp components to identify whether or not the components are based upon the new florida leadership standards, especially technology; and the isllc educational standards; and (b) further research on florida school districts providing a mentor principal and support team; professional development, and a performance-based experience to their current assistant principals who participate in an appp, thus ensuring best practices in the appp and improving the quality of their future principals

Metalinguistic awareness (MA) in the context of the present study is the ability to deconstruct and analyze a language's intricate systems, and by doing so, better understand how these systems work. More specifically for the present study, the investigation focused on preservice teachers' MA in relation to grammar and its importance for their future students' understanding of language. Language is at the core of any content area in students' academic lives and it will continue to permeate all aspects of their studies at all ages. As such, language-related issues should be at the front and center of preservice teachers' preparation. The present study, a quasi-experimental one-group pretest-posttest (Shadish, Cook & Campbell, 2002) investigated the metalinguistic awareness of preservice teachers who were enrolled in a face-to-face, undergraduate applied linguistics course at an urban research university in the United States. The metalinguistic awareness in the scope of the present study was directly related to the grammar knowledge of participants, and it was measured by an adapted instrument called ALAT. The results of the current study demonstrate that overall increase of MA is feasible (as attested by the results from research question 1). Nevertheless, further investigations (research questions 2, 3, 4, and 5) demonstrated that teachers' levels of metalinguistic awareness vary significantly. These results echoed previous findings that demonstrated that preservice teachers are not language-knowledgeable enough to deal with myriad issues that involve language, both in relation to students who are native speakers of English and also concerning ELs (Kolln & Hancock, 2005; Nutta et al., 2012; Pappamihiell, 2007). Preservice teachers' lack higher level metalinguistic awareness, as evidenced by their limited ability to explain grammar errors and use proper metalanguage while doing so. The main implication of the present study lies in the recommendation that more can and should be done in order to ensure that preservice teachers are receiving the appropriate amount of language-oriented preparation during their college years. The present study offers a confirmatory perspective to previous research findings which found that preservice teachers are not knowledgeable enough in relation to language. Previous studies also pointed out to this lack of preparation as a generator of feelings of inadequacy and anxiety in preservice teachers while foreseeing their future students' language struggles. Nonetheless, the present study also demonstrates that improvement can be achieved in regard to MA teacher preparedness in relatively little amount of time, especially for recognition of grammatical items such as parts of speech and parts of sentence. However, the findings demonstrate that more time is needed to ensure better results for complex grammar analyses such as explanation of grammatical errors.

Dense medium cyclones (DMCs) have become the workhorse of the coal preparation industry due to their high efficiency, large capacity, small footprint and low maintenance requirements. Although the advantages of DMCs make them highly desirable, size-by-size partitioning data collected from industrial operations suggest that DMC performance can suffer in response to fluctuations in feed coal quality. In light of this problem, a multi-stream monitoring system that simultaneously measures the densities of the feed, overflow and underflow medium around a DMC circuit was designed, installed and evaluated at an industrial plant site. The data obtained from this real-time data acquisition system indicated that serious shortcomings exist in the methods commonly used by industry to monitor and control DMC circuits. This insight, together with size-by-size partition data obtained from in-plant sampling campaigns, was used to develop an improved control algorithm that optimizes DMC performance over a wide range of feed coal types and operating conditions. This document describes the key features of the multi-stream monitoring system and demonstrates how this approach may be used to potentially improve DMC performance. / Master of Science

This objective of this project was to develop a new dewatering device that could produce a lower moisture content and better fine particle recovery than current technology. To meet this goal, a hyperbaric horizontal belt filter was designed and constructed over the course of 18 months. Once built, the filter was then thoroughly tested to determine operational capabilities. The test data showed that the lowest moisture content that could be achieved with a coarse feed (minus 1 mm screen-bowl centrifuge feed) was 8.8%. This value could be further reduced to 8.2% and capacity increased with the use of dewatering aids. When testing with a fine feed (minus 0.15 mm column product feed), the lowest moisture content was 35% without chemicals and 29% with chemicals. A 50/50 mixture by volume of coarse and fine feeds was artificially created and provided a moisture of 10.8%, which was reduced using reagents to 8.4%. The machine provided a very high recovery rate for all feed materials. Of the coal input, no less than 94% of it reported to the dry product. The pressure used to dewater the coal was the controlling factor for the air consumption of the unit. The data from these tests suggest that a full size production unit is feasible, although the power requirements for gas compression would be high. / Master of Science

Recent hydrodynamic studies suggest that small air bubbles can be used to improve the performance of column flotation. Tests carried out at Virginia Tech during the past several years have shown that various types of inline motionless (or static) mixers can successfully produce microbubbles for column flotation. Unfortunately, few guidelines exist for selecting the proper size and type of motionless mixer for generating microbubbles. In the present work, the mean bubble size produced by various types of in-line motionless mixers has been experimentally determined over a wide range of operating conditions and generator geometries. Test results indicate that generator performance is described by a series of expressions derived from a dimensional analysis. These expressions demonstrate that bubble diameter is primarily determined by the generator geometry and a dimensionless term known as the Weber number. Tests have also been conducted to determine the reduction in the performance of centrifugal pumps under air admitting conditions. A semi-empirical pump model has been utilized which allows the proper size of pump to be selected for microbubble generation. This information should prove useful for the design and operation of microbubble generation circuits on an industrial scale. / Master of Science

<p> Part One deals with thin films of SnO₂ which were prepared by ion-beam sputtering, reactive sputtering and anodic oxidation. The films were found to be either amorphous or crystalline in their prepared state. </p> <p> The structure of the as-deposited amorphous films, as revealed by transmission electron microscopy, presented interesting features: there was a continuous structure in the case of high-temperature deposition, whereas an "island structure" was revealed in the case of low-temperature deposition. Furthermore, heat treatment of films having an "island structure" showed this structure to be maintained provided the heating was done with unsupported films, while the structure became continuous when heat treatment was performed on supported specimens. </p> <p> The crystalline form of the films has been worked out, and found to generally be cassiterite; nevertheless a phase different from cassiterite has been occasionally noticed during this work. In some cases it could be tentatively identified as SnO, while other cases it remains unidentified. Crystallization temperatures found here are somewhat different from those indicated in the literature, namely: 500, 300, 225ºC according to substrate temperature and nature and type of heat treatment. Anodic oxidation of tin has been performed(apparently for the first time) in a non-solvent electrolyte, the films being consistently crystalline. </p> <p> The results obtained in the case of films deposited on water-cooled substrates, have revealed a dependence of film structure on film thickness and this effect has been confirmed in supplementary experiments. Thus thick films appear to crystallize spontaneously at room temperature. </p> <p> Part Two deals with radiation damage studies. Our experiments on krypton-ion bombarded SnO₂ films show that amorphous specimens remain amorphous following ion bombardment. The electron-microscope evidence of whether crystalline SnO₂ is amorphized by ion bombardment was tentatively negative, while the gas-release evidence was strongly negative. </p> Part Three deals with diffusion in inert-gas implanted SnO₂. In the first section we give the theoretical background that enabled us to deduce from our experiments rough estimates of the melting temperature, self-diffusion temperature. and activation-energy for self-diffusion of the less mobile ion in SnO₂. In particular, we obtain the following results: </p> <p> T_melting = 2600 - 3000ºK </p> <p> T_self-diffusion = 1480 - 1870ºK for a 2 min. time scale and 134±44Å distance scale. </p> <p> ∆H_self-diffusion = 87,200 - 131,00 cal/mole </p> <p> Note that the melting point for tine oxide is variously reported in different handbooks to lie between 1400 and 2200ºK. From a comparison with other work we have concluded that our value for ∆H is very likely that for oxygen-ion diffusion. </p> / Thesis / Master of Science (MSc)

<p> The goal of this research project was the development of a protocol for preparation of optically clear organic/inorganic hybrid materials that was amenable to entrapment of lipophilic biomolecules. The protocol involved the acid-catalyzed hydrolysis of mixtures of tetraethylorthosilicate (TEOS) with organosilane precursors, including methyltriethoxysilane (MTES), dimethyldimethoxysilane (DMDMS) and propyltrimethoxysilane (PTMS) in the presence and absence of the polymer additives poly(ethylene glycol) or poly(vinyl alcohol).</p> <p> The effect of organosilane precursors and polymer additives on the optical clarity, hardness and hydration stability of the resulting materials was characterized. It was determined that there was a limit to the amount of organosilane that could be added before the materials exhibited unacceptable characteristics. These limits were 20.0% (v/v) for MTES, 10.0% (v/v) for PTMS, and 5.0% (v/v) for DMDMS. Addition of PEG to these materials at levels up to 10.0% (w/v) resulted in good material characteristics. However, addition of PVA produced opaque materials with poor material properties. The internal environment of the materials was also probed using the environmentally sensitive fluorescent probes 7-azaindole (7AI) and prodan. These studies showed that the method of hydrolysis of the silane precursors and the aging conditions had a dramatic effect on the resulting material.</p> <p> The hybrid materials were used to entrap human serum albumin (HSA) and lipase to determine the effect of organic content on the biological function of these biomolecules. Both biomolecules retained a portion of their native function when entrapped in sol-gel-derived materials, and it was found that both proteins showed enhanced function in the presence of MTES. In the case of lipase, it was also determined that addition of PEG 600 at 10.0% (w/v in the gelation buffer) provided a dramatic increase in activity compared to materials without this additive, likely owing to a direct effect of the PEG on the stability of the entrapped protein.</p> <p> Following studies using bulk glasses, a protocol was developed for the preparation of optically clear sol-gel-derived thin films that was amenable to entrapment of biomolecules. The optimal method involved dipcasting of co-hydrolyzed materials containing 1.0 to 3.0% PEG. By careful control of the viscosity of the casting solution and the rate of film deposition, it was possible to form very stable thin films with excellent physical characteristics. These films were used to entrap the pH-sensitive, ratiometric fluorescent probe dextran-SNARF-1, resulting in a prototype of a fluorimetric pH sensor. Co-entrapment of the probe and lipase into sol-gel-derived thin films resulted in a rapid, reagentless biosensor prototype that could monitor changes in pH due to the enzyme-catalyzed hydrolysis of triglycerides. These results demonstrate that species entrapped in sol-gel derived thin films are suitable for biosensor development.</p> / Thesis / Master of Science (MSc)

<p> Two methods for preparing semiconductor grade copper sulfide films, to be used in low cost thin film solar cells,have been investigated. The sulfurization method involves the controlled chemical conversion of copper films into the desired copper sulfide phase. The other method of evaporating Cu2S pellets is more adaptable for an all evaporated thin film solar cell. The copper sulfide films obtained by these methods were characterized using x-rays, cathodoluminescence, electrical and optical methods. The use of optical method in monitoring the stoichiometry of thin copper sulfide films has been illustrated. The photovoltaic properties of thin copper sulfide films obtained by these methods, were also investigated using Cu2S - Si heterojunctions. The behaviour of these junctions indicates that 900 Ȧ thick copper sulfide film is required for optimum photovoltaic conversion. This result may be of some importance in Cu2S - CdS solar cells in further reducing their thickness. Cu2S - Si heterojunctions can also be used to monitor the properties of copper sulfide, as silicon is a well characterized substrate.</p> / Thesis / Master of Science (MSc)

This explanatory sequential mixed methods study was designed to determine, from the perspective of beginning teachers, the extent to which the COVID-19 pandemic affected their intentions to remain in teaching. There were two additional goals in conducting the study: (a) to determine the key practices, supports, or events that played a role in impacting teachers' intentions to remain in teaching during a crisis; and (b) to determine the key practices, supports, or events teachers believe the district or school could do that might further impact their intention to remain in teaching during a crisis. In Phase 1, a survey was administered to teachers who began employment in the studied district in academic years 2018, 2019, 2020, and 2021. In Phase 2, a semi-structured focus group interview was conducted with volunteer participants who had taken the survey to develop a deeper understanding of the patterns observed from the survey responses. While this study was designed to determine the impact of the COVID-19 pandemic on teachers' intentions to remain in teaching, a statistically significant result was not identified. This study identified practices, supports, and events that impacted beginning teacher retention, focusing on what was effective, ineffective, and could have been added to increase effectiveness. Beginning teachers self-identified that mentorship within their subject and grade level, salary and benefit increases, and supportive cultures were helpful in retention. In contrast, strategies deemed ineffective included a lack of preparation for the challenges that they faced and impractical professional development. Beginning teachers explained that retention might have been increased if school leaders allowed greater opportunities for networking, as well as a greater focus on training teachers in technology and software systems for classroom use.