Abstract The main focus of this work was on exploratory preparation of thermoelectric materials and analyses of their physical properties. A thermoelectric material is capable of converting heat to electricity or vice versa. Usually, narrow band gap semiconductors are good candidates for thermoelectric applications, because such materials have large Seebeck coefficient, reasonably high electrical conductivity and low thermal conductivity. In this work, two different systems were studied, ternary layered tellurides and quaternary derivatives of Tl9BiTe6. I tried to prepare Pb1−xBi2+xTe4 with x = 0.30, 0.10, −0.10 and = 0.30 and Pb1−xBi4+xTe7 with x = 0.15, 0.00, −0.15 and −0.35, and two pure compounds, Pb0.8Bi2.2Te4 and Pb0.9Bi2.1Te4 were obtained. Powder X-ray diffraction was used to confirm the purity of the compounds, and physical properties were measured on cold-pressed samples with densities around 80% of the theoretical value. The figure of merit of the ternary tellurides is comparable to the published values of PbBi2Te4 (0.5 at 600 K). I also investigated the quaternary series Tl8.67PbxBi1.33−xTe6 with x between 0.50 and 1.00. The purity was confirmed by powder X-ray diffraction data, and physical properties were measured on Spark Plasma Sintered (SPS) samples. Low thermal conductivity was observed as well as competitive power factors. The highest ZT value was 0.57 for the compound Tl8.67Pb0.60Bi0.73Te6 at 575 K.

No description available.

No description available.

Ph.d.

In recent years, concerns have been raised about the real effects of credit default swaps (CDS) on the economy. Different from the hitherto accepted view that derivatives are redundant, CDS may affect the credit risk and strategic liquidity decision of the reference entities. In this dissertation, I use a unique, comprehensive sample covering 901 CDS introductions on North American corporate issuers, between June 1997 and April 2009, to address these questions. In chapter 2, I investigate whether CDS trading increases the credit risk of the reference entities. I find that the probability of both a credit rating downgrade and bankruptcy increase after the inception of CDS trading. This finding is robust to controlling for the endogeneity of CDS trading in difference-in-difference analysis, propensity score matching, and treatment regressions with instruments. In further corroboration of our basic results, I explore the mechanism behind the increased credit risk after CDS trading, and show that firms with relatively larger amounts of CDS contracts outstanding, and those with more “no restructuring” contracts, are more adversely affected by CDS trading. In chapter 3, I further investigate the effect of CDS on corporate cash holding policies. U.S. firms are holding more cash than at any time in nearly half a century. I find that CDS trading affects corporate cash holdings. Corporate cash holdings increase after the inception of CDS trading. The impact is significant after controlling for the endogeneity of CDS trading. Moreover, cash-to-assets ratios for firms with larger CDS contracts outstanding, and those with less access to financial market are more affected by CDS trading. The impact of CDS is beyond the direct effect of line of credit on cash holdings. / published_or_final_version / Economics and Finance / Doctoral / Doctor of Philosophy

The research project, The Enzymatic Synthesis of CoA Derivatives Using a New ATP Regeneration System, describes the multiple lab trials conducted to develop an ATP regeneration system using various concentrations of specific substrates and the two enzymes MatB and PrpE. Reactions were combined using different concentrations of ADP, the addition or removal of ADK (adenylate kinase), and the substitution of either MatB or PrpE. Further reactions were combined using trans-crotonyl, trifluoroacetic acid, butyric acid, acetic acid, and creatine phosphokinase. This report also includes the methods used and analysis of the different chromatographs of each sample tested. / text

In the present study, a new "anti-Bredt" bicyclic urea, 1,3-diazabicyclo[3·3·1]nonan-2-one, and an isomeric bond-bridged reference compound 1,8-diazabicyclo[4·3·0]nonan-9-one, were synthesized. The [3·3·1] urea was prepared in two ways. 3-Aminomethylpiperidine was reacted with phosgene. Deprotonation of the precipitated ammonium salt with triethylamine gave the urea. In another method, thermal depolymerization (in vacuo) of a glassy product arising from the reaction of 3-aminomethylpiperidine with diphenyl carbonate afforded the urea. The [4·3·0] urea was obtained through the reaction of diphenyl carbonate with 2-aminomethylpiperidine. No glassy intermediate was observed. The [4·3·0] and [3·3·1] ureas resisted hydrolysis. The former would not polymerize either in bulk or in solution at any temperature with or without initiator catalysts. At 120° and above the [3·3·1] urea bulk polymerized within 30 minutes with or without catalysts. The uncatalysed thermal polymerization gave lower molecular weight polymers in lower yield than the catalysed one. Cationic initiator, phenylphosphonic acid, and anionic potassium tertiary butoxide catalysts gave highest molecular weight polymers. Comparatively, the anionic initiator generated a higher molecular weight polymer than the cationic one. Dibutyltin oxide which is a coordination metal catalyst was also effective in generating high polymer but the yield compared favorably only with the uncatalysed thermal polymerization. The bulk polymerization of the [3·3·1] urea is one of the rare cases of polymerization of a bicyclo [3·3·1] nonan derivative. The mechanism proposed for the thermal polymerization of [3·3·1] urea involved the dissociation of the urea to an aminoisocyanate which then propagated the polymerization. The reaction of 3-aminopiperidine with diphenyl carbonate afforded a urea which was proposed to be a dimer of the desired urea, 1,6-diazabicyclo[3·2·1]octan-7-one. The unsuccessful syntheses of two ureas possessing two nitrogen bridgehead atoms, 1,5-diazabicyclo[3·2·1]octan-8-one, and 1,5-diazabicyclo[3·3·1]nonan-9-one, and another which was seven-membered, 1,3-diazabicyclo[3·2·2]nonan-2-one, were explained in terms of their canonical forms violating Wiseman's rule. However, a nuclear magnetic resonance (NMR) spectrum evidence of the formation of 1,5-diazabicyclo[3·2·1]octan-8-one in the NMR tube was presented.

Η διπλωματική εργασία αφορά στη δημιουργία βάσης δεδομένων για ινδολοκαρβαζολικά και φλαβονοειδικά παράγωγα. Τα δεδομένα που εισήχθησαν στη βάση αφορούν κυρίως στη δράση ινδολοκαρβαζολικών και φλαβονοειδικών αναλόγων στα σύμπλοκα CDKs/κυκλινών σε πολυάριθμες κυτταρικές σειρές. / The purpose of my master was the creation of a database for indolocarbazole and flavones derivates. The data were about the role of indolocarbazole and flavones derivates to the CDKW/cyclin complexes in many cell lines.

Abstract The main focus of this work was on exploratory preparation of thermoelectric materials and analyses of their physical properties. A thermoelectric material is capable of converting heat to electricity or vice versa. Usually, narrow band gap semiconductors are good candidates for thermoelectric applications, because such materials have large Seebeck coefficient, reasonably high electrical conductivity and low thermal conductivity. In this work, two different systems were studied, ternary layered tellurides and quaternary derivatives of Tl9BiTe6. I tried to prepare Pb1−xBi2+xTe4 with x = 0.30, 0.10, −0.10 and = 0.30 and Pb1−xBi4+xTe7 with x = 0.15, 0.00, −0.15 and −0.35, and two pure compounds, Pb0.8Bi2.2Te4 and Pb0.9Bi2.1Te4 were obtained. Powder X-ray diffraction was used to confirm the purity of the compounds, and physical properties were measured on cold-pressed samples with densities around 80% of the theoretical value. The figure of merit of the ternary tellurides is comparable to the published values of PbBi2Te4 (0.5 at 600 K). I also investigated the quaternary series Tl8.67PbxBi1.33−xTe6 with x between 0.50 and 1.00. The purity was confirmed by powder X-ray diffraction data, and physical properties were measured on Spark Plasma Sintered (SPS) samples. Low thermal conductivity was observed as well as competitive power factors. The highest ZT value was 0.57 for the compound Tl8.67Pb0.60Bi0.73Te6 at 575 K.

No description available.