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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Electro-Optical Property Study of Novel Discotic Liquid Crystals Containing 9-{11-[2,3,6,7-Tetrakis(hexyloxy)dibenzo[a,c] phenazinylcarbonyloxyalkyl]}carbazol Moiety

Chuang, Yao-wei 27 July 2007 (has links)
Discotic liquid crystals(DLCs) in this research absorb the light in visible region of spectrum, this characteristic is not found in rod-like liquid crystals. A majority of discotic liquid crystals form columnar mesophases probably due to intense £k-£k interactions of polyaromatic cores. £k-£k interactions are caused by intermolecular overlapping of p-orbitals in £k-conjugated systems, so they become stronger as the number of £k-electrons increases. Three new hexagonal columnar disctic liquid crystals 9-{11-[2,3,6,7-tetrakis(hexyloxy)dibenzo[a,c]phenazinylcarboxyalkyl]} have been successfully synthesized by covalently attaching carbazole moiety to a tetrakis (hexyloxy)dibenzo[a,c]phenazinyl core with an ester group containing different lengths of alkyl spacer having 3,6,and 11 carbon atoms. In order to set up a basic data base, we measure and analyze the discotic liquid crystals via various instruments.In addition, we also utilize both simulation systems of MMM and QMM to predict several molecular dynamics and properties such as: vibration, rotation, motion and heat of formation and so on.So we can see more depth inside how the concentration effects on the geometry structure arrangement of the discotic liquid crystals.
2

Identifying Calcium-Binding Sites and Predicting Disulfide Connectivity

Deng, Hai 06 August 2007 (has links)
Most questions in proteomics require complex answers. Yet graph theory, supervised learning, and statistical model have decomposed complex questions into simple questions with simple answers. The expertise in the field of protein study often address tasks that demand answers as complex as the questions. Such complex answers may consist of multiple factors that must be weighed against each other to arrive at a globally satisfactory and consistent solution to the question. In the prediction of calcium binding in proteins, we construct a global oxygen contact graph of a protein, then apply a graph algorithm to find oxygen clusters with the fixed size of four, finally employ a geometry algorithm to judge if the oxygen clusters are calcium-binding sites or not. Additionally, we can predict the locations of those sites. Furthermore, we construct a global oxygen contact graph including oxygen-bonded carbon atoms of a protein, then apply a graph algorithm to find local biggest oxygen clusters, finally design another geometric filter to exclude the non-calcium binding oxygen clusters. In addition, we apply observed chemical properties as a chemical filter to recognize some non-calcium binding oxygen clusters. In order to explore the characteristics of calcium-binding sites in proteins, we conduct a statistic survey on four datasets derived from 1994 to 2005 about the geometric parameters and chemical properties of calcium-binding sites. In the prediction of disulfide bond connectivity, we analyze protein sequences to predict the folding of proteins relative to the cystines using nearest neighboring methods. we extend a new pattern-wise method to all available template proteins, and find global pattern of pairing cysteines with a new descriptor of cysteine separation profile on protein secondary structure.

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