Search

Reflection of light by silicon surfaces without antireflection coatings results in a loss of over 35% of the total solar energy. Several antireflection techniques have been used to reduce the reflection of silicon including antireflection coatings, textured surfaces, and porous surfaces. These techniques require either expensive equipment or corrosive chemicals. Therefore, there is a need for an inexpensive, quick, simple, safe and environmentally friendly method for making textured silicon to achieve broadband antireflection for solar cell applications. The goal of this dissertation research was to establish a novel plasma electrolysis process to create textured silicon surfaces without using corrosive or toxic chemicals to achieve broad-spectrum anti-reflection for solar cells and to understand the chemical reactions and physical processes that occur during plasma electrolysis for making textured silicon. Textured or rough surfaces can reduce light reflection due to light scattering or destructive interference. Textured and porous silicon surfaces were fabricated using different solvent compositions and electrolytes. The obtained surfaces were characterized using UV-2600 spectrophotometer with an integrating sphere, SEM, AFM, and Raman spectroscopy. It was found that the electrolyte used and solvent composition were the main factors that influence the obtained surface structure on silicon substrates. When textured surfaces were formed during plasma electrolysis, chemical reactions were dominant. When cratered or porous silicon surfaces were obtained, the physical processes were dominant. In this work, the chemical reactions and physical processes that occur during plasma electrolysis have been decoupled for the first time and enabled the creation of different surface morphologies (e.g., textured, cratered and porous) without corrosive chemicals.

Numerous troponin T (TnT) isoforms are generated by alternative RNA splicing primarily in its NH2-terminal hypervariable region, but the functions of these isoforms are not completely understood. In this dissertation work, calcium and terbium binding behavior of several forms of TnT were investigated by spectroscopic and radioactive techniques. Chicken breast muscle TnT binds calcium and terbium through its NH2-terminal Tx motif (HEEAH)n with high affinity (10-6 mM) and fast on-rate (106 - 107 M-1 s-1). Chicken leg muscle TnT and a human cardiac TnT NH2-terminal fragment, which both lack the Tx motif on their NH2-terminal regions, do not have affinities for calcium in the physiological range. Computational predictions on TnT N47 suggest that the TnT NH2-terminal region might fold into an elongated structure with at least one high affinity metal ion binding pocket comprised primarily of the Tx motif sequence and several lower affinity binding sites. In addition, calcium binding to TnT N47 might alter its conformation and flexibility. Luminescence resonance energy transfer measurements and other experimental observations are consistent with the computational predictions suggesting the computational simulated atomic model is reasonable. TnT mutations are responsible for 15% of familiar hypertrophic cardiomyopathy (FHC) cases with a phenotype of relatively mild hypertrophy, but a high incidence of sudden death. Detection of those genetic mutations would facilitate the clinical diagnosis and initiation of treatment at an early stage. This dissertation also investigated a novel hybridization proximity assay (HYPA) combining molecular beacon and luminescence resonance energy transfer (LRET) technologies. Experimental results suggest that a shared stem probe design produces a more consistent response upon hybridization, whereas the internally labeled probe was less consistent, but can yield the highest responses. Using the optimally designed molecular probes, the HYPA provides a detection of alterations in nucleic acid structure of as little as a single nucleotide. This novel HYPA is expected to expand its applications in the analysis and screening of genetic diseases.