Master of Sciences (Engineering), Case Western Reserve University, 2016, Macromolecular Science and Engineering

In order to fulfill the urgent need of new generation capacitor film, the co-extruded multilayer film being proposed possess several crucial factors high dielectric constant, low loss and high operation temperatures. In order to get deep understanding of prevailing dielectric performance in multilayer film, the breakdown strength, dielectric lifetime measurement and D-E loop measurement were conducted. Based on the dielectric properties of multilayer capacitor films, the interfacial polarization effect on the insulation properties are revealed. In the PSF/PVDF multilayer films, two factors can play an important role on the insulation properties. The blocking electrode, PSF played an important role to accumulate the charge in the interfaces. And the PVDF layer also played the other role serving as the resource of the accumulating charges. Consequently, the thicker PVDF and PSF layers will result in higher interfacial polarization than thinner PVDF and PSF layers. Because these interfacial charges can effectively trap electrons injected from the (negative) electrode under a high electric field, the volume resistivity of PSF/PVDF multilayer films with thicker PVDF/PSF layers will be higher than those with thinner PVDF/PSF layers. In order to further prove the interfacial polarization effect on insulation properties, the TSDC and dc conductivity measurement are employed. Those experiments prove the existence of interfacial charges and its effect on overall conductivity. It shows 32 layer- multilayer films have better insulation properties than 256 layer-films through three different temperatures and fields. That can be attributed to the more accumulation of interfacial polarization in 32 layer- multilayer films as 32 layer MLF has thicker blocking electrode, PC, to hold interfacial charges. And also the pre-poling experiment gave a clear illustration that interfacial charges built counter field in the layer structure which reduces the conducting current through the (open full item for complete abstract)

Committee: Lei Zhu (Advisor); Eric Baer (Committee Member); Donald Schuele (Committee Member) Subjects: Energy; Engineering; Polymers

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2012, Biological Sciences

Many hairpin and internal RNA 3D motif structures are recurrent, occurring in various types of RNA molecules, not necessarily homologs. Although usually drawn as single-strand “loops” in RNA 2D diagrams, recurrent motifs share a common 3D structure, but can vary in sequence. It is essential to understand the sequence variability of RNA 3D motifs in order to advance the RNA 2D and 3D structure prediction and ncRNA discovery methods, to interpret mutations that affect ncRNAs, and to guide experimental functional studies. The dissertation is organized into two parts as follows. First, the development of a new online resource called RNA 3D Hub is described, which is intended to provide a useful resource for structure modeling and prediction. It houses non-redundant sets of RNA-containing 3D structures, RNA 3D motifs extracted from all RNA 3D structures, and the RNA 3D Motif Atlas, a representative collection of RNA 3D motifs. Unique and stable ids are assigned to all non-redundant equivalence classes of structure files, to all motifs, and to all motif instances. RNA 3D Hub is updated automatically on a regular schedule and is available at http://rna.bgsu.edu/rna3dhub. In the second part of the dissertation, the development of WebFR3D (http://rna.bgsu.edu/webfr3d), a new webserver for finding and aligning RNA 3D motifs, is described and its use in a biologically relevant context is then illustrated using two RNA 3D motifs. The first motif was predicted in Potato Spindle Tuber Viroid (PSTVd), and the prediction was supported by functional evidence. The second motif had previously been undescribed, although it is found in multiple 3D structures. RNA 3D Hub, RNA 3D Motif Atlas, and the bioinformatic techniques discussed in this dissertation lay the groundwork for further research into RNA 3D motif prediction starting from sequence and provide useful online resources for the scientific community worldwide.

Committee: Neocles Leontis PhD (Advisor); Craig Zirbel PhD (Committee Member); Paul Morris PhD (Committee Member); Scott Rogers PhD (Committee Member); Raymond Larsen PhD (Committee Member) Subjects: Bioinformatics; Biology