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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.
131

Using Hydrogen-Bonding Interactions to Control the Peptide Miscibility and Secondary Structures

Lu, Yi-syuan 07 August 2012 (has links)
In this study we synthesized poly(tyrosine) (PTyr) through living ring-opening polymerization of £\-amino acid-N-carboxyanhydride and then blended with poly(4-vinyl pyridine) (P4VP) homopolymer in N, N-dimethylformamide (DMF) and methanol solutions to control the miscibility behavior and the secondary structures of poly(tyrosine). Infrared spectrum analysis suggests that the mixture of PTyr/P4VP possesses strong hydrogen-bonding interaction between the hydroxyl group of PTyr and the pyridine group of P4VP. DSC analyses indicate that these PTyr/P4VP complexes from methanol solution always have higher glass transition temperatures than the corresponding PTyr/P4VP miscible blends obtained from DMF solution. We proposed that the polymer chain behavior of PTyr/P4VP blend from DMF solution is the separated random coil and thus the PTyr chain possesses the random coil secondary structure after solvent evaporation. However, by increasing the hydrogen bonding for PTyr/P4VP complex from methanol solution, inter-polymer complex aggregate is proposed and the corresponding chain behavior enhances the intermolecular hydrogen bonding interaction of PTyr with P4VP that results in the £]-sheet conformation based on Fourier transforms infrared (FTIR), solid state nuclear magnetic resonance (NMR) spectroscopy, and wide-angle X-ray diffraction analyses.
132

Pricing risky bonds under discrete time models

Kuo, Chia-Cheng 12 July 2005 (has links)
Credit risk of derivative securities includes the risk of underlying company and the risk of seller's nonfulfilment of contracts. Take bonds for example, we regard Treasury bills as default-free bonds, and corporate bonds as risky bonds. When the liability of property of derivative securities underlying company is less than 1, we regard the company is of bankruptcy. And then the seller of derivative securities will break the contract. The essay extends two period risky bonds pricing valuation of Jarrow and Turnbull(1995) to multiperiod situation, and derive arbitrage-free condition. Furthermore, we derive formulae of risky bonds prices by assuming the logarithm of the odds ratio of an underlying company's bankruptcy probability satisfies an AR(1) or MA(1) processes. Empirical data of Rebar, Chinarebar, Ceon are studied, time series models are established for logarithm of odds ratios. In most cases, we find that the log odds ratios can be well fitted by AR(1) models.
133

Security Choice and Convertible Bond Issuance Announcement Effect

Chao, Yu-Hsin 10 February 2003 (has links)
The objects this thesis want to study can be separated into two parts. The first part is investigating why firms choose to issue convertible bond. We use the public financial information and macroeconomics factors to establish a security choice model. In this security choice model, we can understand the motivation of issuance and investors¡¦ expectation of security type (equity-like or debt-like) which will be issued. The second part of this thesis is about convertible bond issuance announcement effect. We want to know if the public information and the pre-issuance security type expectation would affect the announcement effect. Following is the conclusions: (1) We find that less information asymmetry, less agency cost, more operating risk will lead to higher probability of equity-like security issuance. (2) Most convertible bonds issued in Taiwan are more debt-like. (3) Equity-like convertible bonds issuances have negative announcement effect. The issuances different from expectation will lead to more negative price effect, especially those debt-like firm but issue equity-like security. (4) The variables that can explain security choice may not explain the announcement price effect.
134

Sharing of figurative language themes in expert therapy: occurrence and effect on client experiencing and therapeutic bond

Cardin, Scott Ashley 30 September 2004 (has links)
The purpose of this study was to examine the use and effect of figurative language discourse in examples of expert therapy. More specifically, one of the main reasons for conducting this study was to describe figurative language discourse, its production, use, and potential effects on the therapeutic relationship and client experiencing. Training videos were selected and transcribed using criteria for selection of examples of expert therapy. Fifty-six excerpts, each two-minutes in length, were taken from the transcribed therapy sessions and used for the analyses. One set of raters was trained to identify instances of figurative language and make ratings of shared theme. Another set of raters was trained to use the Experiencing Scales and the Working Alliance Inventory on the transcribed excerpts. Analyses were conducted to investigate the frequency of use and relationship between therapist and client figurative language dialogue. Results indicated that the majority of figurative language used in examples of expert therapy is metaphoric in nature. Additionally, it was found that the majority of figures of speech were frozen in meaning or were commonly used. A small percentage of figures of speech were shared conceptually between the therapist and the client. Regarding the shared figurative language, a statistically significant difference between therapists and clients with regard to their production of shared figurative language was found and indicates that use of shared figurative language by expert therapists may be a subtle and indirect way in which therapeutic alliance is initially established as well as maintained. It may also represent how expert therapists follow content of the therapy session. In addition, a regression analysis conducted to determine if there is a relationship between shared figurative language and ratings of therapeutic alliance did not meet statistical significance. Overall, the results of this study provide preliminary findings with regard to what type of figures of speech expert therapists use and give a clear direction in terms of the next direction for research. Additionally, this experiment provides direction for the type of methodology that should be utilized in future research.
135

The Influence of Rational Choice on Juvenile Delinquency: Social Bond as Mediator and Demographic Characteristics as Moderator

Wu, Shu-hua 23 June 2008 (has links)
The rational choice theory provides good explanations of the factors on juvenile delinquency: the decision-making mechanism of delinquency is as same as the other activities, is based on the rationality. Juveniles will increase the probability of delinquency if the expected utility exceeds the expected cost; oppositely, they will reduce the probability of delinquency if the expected cost exceeds the expected utility. This proposed research from the perspective of rational choice is to study the influence between juveniles¡¦ individual rationality and delinquency and intend to provide the reasonable explanation to provide the reasonable explanation to juvenile delinquency. But besides individual rational choice factor, the degree of social bond will also have the influence to juvenile delinquency, therefore this research will also simultaneously discuss the mediate effects of the society bonds to the rational choice and juvenile delinquency. Our results suggest that the rational choice (perception of risks and self-imposed costs) and the social bonds (attachment and belief) are negatively related to juvenile delinquency. The society bonds (attachment and belief) could mediate the effects of the rational choice and juvenile delinquency. The interaction between demographic characteristics and rational choice has few effect on juvenile delinquency.
136

A Multi-phase Approach for Disulfide Bond Prediction

Chung, Wei-Chun 25 July 2009 (has links)
Disulfide bond information can help the prediction of protein secondary structure, tertiary structure and all-atom coordinates. Most of previous works focused on either state classification or connectivity prediction with some assumption that some constraints were added to make the problem solvable in reality. In this thesis, we propose a multi-phase approach to solve the problem. Our method can export the number of bonds and achieve 90.7% accuracy in the state classification. For the connectivity prediction problem, we use the number of bonds we predict as a base to decide bond pairs. For overcoming the ratio imbalance of samples, we propose a down-sampling method to reducing processing time. Finally, we perform the weighted graph matching algorithm to obtain the bonding pattern, which achieves 63.5% accuracy. We also achieve 48% accuracy for the thorough prediction. Our method is validated by the datasets derived from SWISS-PROT and PDB. The results are better than the previous works.
137

The Application of Hydrogen Bonding in Polymer Blend and Composites

Liu, Wei-Chen 27 January 2010 (has links)
Differential scanning calorimetry (DSC), 13C solid state nuclear magnetic resonance (SSNMR), one- and two-dimensional fourier transform infrared spectroscopes (FT-IR), Gel Permeation Chromatography (GPC) have been used to investigate the miscibility behavior and specific interactions of Poly(3-hydroxybutyrate), (PHB) blending with poly(styrene-co-vinyl phenol), (PS-co-PVPh) through hydrogen bonding complex upon varying the vinyl phenol contents in copolymer. We describe FT-IR spectra reveal that hydrogen bonding between carbonyl and phenol. A miscibility window exists when the vinyl phenol fraction in the copolymer is greater than 20 mol% in the PHB/PS-co-PVPh blend system, as predicted using the Painter¡VColeman association model. The vinyl-terminated benzoxazine (VB-a), which can be polymerized through ring opening polymerization, was synthesized through the Mannich condensation of bisphenol A, formaldehyde, and allylamine. This VB-a monomer was then blending with epoxy resin, followed by thermal curing concurrently, to form epoxy/VB-a copolymers network. To understand the curing kinetics of this epoxy/VB-a copolymer, dynamic differential scanning calorimetry measurements were performed by Kissinger and Flynn-Wall-Osawa methods. The FTIR analyses revealed the presence of thermal curing reactions and hydrogen bonding interaction of epoxy/VB-a copolymers. Meanwhile, the significant enhancement of the ring opening and allyl polymerizations of the epoxy was observed. For these IPNs, DMA and TGA results indicate that the thermal properties increase with the increase of VB-a contents in epoxy/VB-a copolymers.
138

Development of ruthenium catalyzed hydrogenative carbonyl addition reactions

McInturff, Emma Leigh 30 June 2014 (has links)
Metal-catalyzed, hydrogenative methods for carbon-carbon bond formation are attractive alternatives to traditional carbonyl addition reactions. Through in situ generation of aldehyde and organometallic species, these redox-triggered reactions circumvent the need for preactivation of reactive partners, thereby providing a more atom economic, efficient approach to carbonyl addition products. Efforts have been focused on the development of ruthenium-catalyzed coupling reactions of primary and secondary alcohols to basic feedstock chemicals and easily accessible and stable unsaturated compounds. To perform highly stereoselective reactions, investigation into the factors that control stereoselectivity in ruthenium catalyzed transfer hydrogenative couplings was undertaken. As a critical tool for the construction of organic molecules, modernizing methods for carbonyl addition can contribute to the evolution of synthetic organic methodology. / text
139

Studies on vitamin B12 compounds

Williams, F. R. January 1970 (has links)
No description available.
140

Two Essays on the Corporate Bond Market

Theocharides, George January 2006 (has links)
This dissertation consists of two papers. The first paper examines the propagation of firm-specific shocks as well as market-wide shocks between 1995-2003 using Treasury and corporate bond market data. It then tests the implications of previously proposed models of contagion. I find little support for the industry and counterparty structure hypothesis, suggesting that fundamentals do not generate contagion. Consistent with the information transmission, rebalancing, and liquidity-shock hypotheses, I find evidence of flight to quality during the event periods. However, in contrast to the prediction of the liquidity-shock channel, the corporate bond market, on average, seems to be more liquid during event periods (evidenced by higher trading volume, trading frequency, and mean bond age). Furthermore, there are no significant changes in the trading of assets with the low transaction costs, which is contrary to the rebalancing theory. These findings are more in favor of the correlated information channel as a means of inducing contagion.The second paper examines the effect of liquidity on corporate bond prices using the newly formed TRACE data set. In the spirit of Acharya and Pedersen's (2005) liquidity-adjusted capital asset pricing model (LCAPM), I examine the impact of multiple sources of risk on corporate bond prices. The results do not lend strong support for the existence of liquidity risk in the corporate bond market or for the LCAPM, especially when liquidity is captured using the trading frequency, trading volume, and turnover. Contrary to the predictions of the LCAPM, more illiquid portfolios do not have higher values for the three liquidity betas; betas that capture the commonality in liquidity with the market, the sensitivity in returns with the market-wide liquidity, and the liquidity sensitivity with the market returns. Furthermore, after running cross-sectional regressions I do not find strong evidence either for the validity of the model or that liquidity risk does matter for the corporate bond prices.

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