The present study exploits two different molecules as biorecognition elements for biosensing. In the first case, a protein biosensor was performed using maltose-binding protein (MBP). The ability to manipulate protein function rationally also offers the possibility of creating new proteins of biotechnological value. Our design has been used to test the understanding of allosteric transitions in proteins. Here we examined a simple conformational change that can represent the biorecognition principle for a reagentless biosensor. Previously, modular strategies for transducing ligand-binding events into fluorescent and electrochemical responses have been reported. Starting with a study of the conformational changes of MBP this research will further develop electrochemical maltose biosensors. The responses of four individual mutations (K46C-MBP-MT, N282C MBP-MT, Q72C-MBP-MT; and K25C-MBP-MT) were evaluated using square wave voltammetry. The possibility of using this type of transduction mechanism for sensor configurations and analyte specificity is discussed.The second part of this work involves SELEX (systematic evolution of ligands by exponential enrichment) and aptamers as biorecognition molecules. As a result of the SELEX method, we can obtain oligonucleotide sequences (aptamers) with recognition properties similar to antibodies. These synthetic elements play an important role in molecular recognition because of their capability for specifically binding of a target molecule. A new approach for the separation step has been performed, termed Soluble-SELEX. This new SELEX method uses hybridization as partitioning mechanism for separating the bound and unbound DNA members from the target-molecule. Hybridization procedure has been evaluated by fluorescence studies as partitioning mechanism for SELEX method. Herein, we exploited the incorporation of an aptamer for biosensing detection of a specific target molecule. Three different transduction methods such as fluorescence, electrochemistry and surface plasmon resonance (SPR) were evaluated. In all three cases, the biosensing procedure was successful.In conclusion, this research has evaluated the translation of a fluorescent biosensor into an electrochemical biosensor using maltose-binding protein as biorecognition element. On the other hand, a new SELEX method has been developed. However, future improvements are required in order to optimize the method. As result of SELEX a new avidin-aptamer was selected and three different transduction systems were employed to construct fluorescent, surface Plasmon resonance and electrochemical biosensors. / El presente estudio utiliza dos moléculas diferentes como elementos de bioreconocimiento. En el primer caso, un biosensor basado en proteínas fue desarrollado utilizando la proteína periplasmica de unión a maltosa (MBP = maltose-binding protein). La habilidad para manipular racionalmente la función de una proteína también ofrece la posibilidad de crear nuevas proteínas con valor biotecnológico. Nuestro diseño proteico ha sido usado para evaluar cambios alostéricos en proteínas. Este estudio evalúa un simple cambio conformacional el cual puede ser usado como el principio transductivo para un biosensor. Diferentes estrategias de transducción usando fluorescencia y electroquímica en eventos de reconocimiento entre la proteínas periplasmicas de unión y el ligando, han sido previamente reportadas. Esta investigación inicia con el estudio de los cambios conformacionales de MBP, continuando con el desarrollo de un biosensor electroquímico para maltosa. La señal de cuatro diferentes mutantes (K46C-MBP-MT, N282C MBP-MT, Q72C-MBP-MT; y K25C-MBP-MT) fue evaluada usando voltimetría de onda cuadrada. La posibilidad de usar este tipo de transducción mecánic (distancia) para la configuración de biosensores y la respectiva especificidad analítica es discutida. La segunda parte de este trabajo incluye el método SELEX (systematic evolution of ligands by exponential enrichment) y aptameros como moléculas de bioreconocimiento. Como resultado de el método SELEX, podemos obtener secuencias de oligonucleótidos (aptameros) con propiedades de reconocimiento similares a los anticuerpos. Estos elementos sintéticos, tienen un importante rol en el reconocimiento molecular por su capacidad de unión específica a la molécula blanco. Un nuevo mecanismo para el paso de separación ha sido realizado, y llamado SELEX-Soluble. Este nuevo método SELEX usa la hibridización como mecanismo de separación para dividir los oligonucleótidos de DNA que no se unen y los que se unen a la molécula blanco. El procedimiento de hibridización y su uso como mecanismo de separación en el método SELEX ha sido evaluado a través de estudios de fluorescencia. Este estudio también explora la incorporación de un aptamero como elemento de reconocimiento en un biosensor. Tres diferentes mecanismos de transducción has sido evaluados: fluorescencia, electroquímica y resonancia de plasmon superficial (SPR). En los tres casos una excelente señal fue reportada. En conclusión, esta investigación ha evaluado la transferencia de una biosensor de fluorescencia a un biosensor electroquímico, utilizando la proteína periplásmica de unión a maltosa como elemento de bioreconocimiento. De otro lado, un nuevo método SELEX ha sido desarrollado. Sin embargo, futuras mejoras son requeridas para optimizar el método. Como resultado del método SELEX realizado un nuevo aptamero para avidita ha sido seleccionado y tres diferentes sistemas de transducción ha sido empleado para construir tres diferentes biosensores (fluorescencia, electroquímica y SPR).

The purpose of this study is to examine prospective mathematics teachers' knowledge development and beliefs changes for teaching fraction division through the undergraduate mathematics method course to the field practice. Further, it reveals the correlation between the knowledge development and beliefs changes. Therefore, this study uses a qualitative methodology. I analyze the data from two time periods using three steps. In the method course period, interviews concerning knowledge and beliefs are triangulated with the tests, surveys, concept mapping and the writing assignment. There are two steps in this time period. First, I focus on a total of 27 prospective teachers' subject matter knowledge (SMK), including common content knowledge (CCK) and special content knowledge (SCK), and its development. Further, I examine their beliefs changes towards fraction division and mathematics teaching and learning during the method course. Next, I choose six participants from the total 27, based on different mathematics achievement. I do this to identify 1) whether CCK differences impact SCK development and 2) whether SCK development influence beliefs changes in the method course. In the field practice period, classroom observation of fraction division is triangulated with the interviews. I follow up one prospective teacher in his field practice and focus on the way his beliefs influence his teaching behavior and the development of the pedagogical content knowledge (PCK), through the teaching. The results indicate that the prospective teachers developed both CCK and SCK in their method course. Their beliefs towards to teaching and learning fraction division progress from procedural-oriented to conceptual-oriented. The knowledge development and beliefs changes derived from the different learning experiences from their past school experiences and method course. Moreover, prospective teachers who had high CCK developed his/her SCK significantly. Thus, his/her beliefs changes became more significant. Further, the prospective teacher's beliefs changes in the method course influenced the way of teaching behavior in the field practice and SCK impacts PCK in teaching. On the other hand, field practice changed prospective teacher's beliefs and the development of PCK. Therefore, further attention is called for in the prospective teachers' knowledge transition and beliefs changes from a student to a future teacher.

Thesis (M.A.)--Texas State University-San Marcos, 2008. / Vita. Appendices: leaves 74-79. Includes bibliographical references (leaves 80-84). Also available on microfilm.

Thesis (MA)--University of Montana, 2009. / Contents viewed on November 30, 2009. Title from author supplied metadata. Includes bibliographical references.

Thesis (Ph.D.)--University of Wollongong, 2009. / Typescript. Includes bibliographical references: leaf182-203.

Thesis (M.Ed.)--Memorial University of Newfoundland, 2001. / Bibliography: leaves 83-85. Also available online.

Thesis (Ph. D.)--Rutgers University, 2009. / Includes bibliographical references.

Thesis (Honors)--College of William and Mary, 2009. / Includes bibliographical references (leaves 159-176). Also available via the World Wide Web.

Thesis (Ph. D.)--School of Earth and Atmospheric Sciences, Georgia Institute of Technology, 2004. Directed by Rong Fu. / Includes bibliographical references (leaves 119-131).

Thesis (M.S.)--Joint Program in Oceanography/ Applied Ocean Science and Engineering, Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution, 2004. / Includes bibliographical references.