Thesis (Ph. D.)--University of Wisconsin--Madison, 1958. / Typescript. Abstracted in Dissertation abstracts, v. 18 (1958) no. 3, p. 838. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 175-179).

Dissertation (Ph.D.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.

In organometallic study, activation of C-F bond is an interesting subject, especially in fluoro-substituted propyl groups, because of their different reactivityn from fluoro-substituted methyl and ethyl groups. In this thesis, fluorinated propyl groups were studied on a Cu(111) surface under ultrahigh vacuum (UHV) conditions. We have examined the kinetics of the £]-elimination reaction in CF3CF2CH2-Cu, CHF2CF2CH2-Cu, and CF3CH2CH2-Cu. These species all decompose via £]-elimination to give CF3CF=CH2, CHF2CF=CH2, and CF3CH=CH2. The first two species undergo £]-fluoride elimination and the third one undergoes £]-hydride elimination. The difference in activation energies between the first two accounts for the charge separation (R-C£]+£_¡KF−£_¡KM+£_) in the transition state proposed by Gellman. The activation energies for £]-hydride elimination (CF3CH2CH2-Cu) and £]-fluoride elimination (CF3CF2CH2-Cu) was also compared. The activation energy for £]-fluoride elimination is found to be lower than that of £]-hydride elimination. In the studies of reaction pathways for perfluoropropyl groups (n-C3F7-Cu and i-C3F7-Cu) on Cu(111), we discovered novel chemistry in TPD. n-C3F7-Cu undergoes Cu-C homolytic cleavage (radical desorption) at 340 K, whereas i-C3F7-Cu eliminates the £]-fluorine at 365 K. By changing the Cu-C bond length in the i-C3F7-5Cu models their IR spectra was calculated. We discover that the IR of i-C3F7-5Cu with shorter Cu-C bond (1.728Å) is more similar to the experimental IR spectra. That demonstrates the bond strength of Cu-C bond of i-C3F7-Cu is too strong to undergo Cu-C homolytic cleavage at 340 K. Hence, £]-F decomposition becomes the favorite pathway to i-C3F7-Cu because there are more £]-F atoms available in this moiety.

Zugl.: Giessen, Univ., Diss., 2007

Zugl.: Giessen, Univ., Diss., 2007

Universiẗat, Diss., 2007--Giessen.

Universiẗat, Diss., 2007--Giessen.

Low levels of biogenic amines occur naturally, but high levels (FDA sets 50 ppm of histamine in fish as the maximum allowable level) can lead to scombroid poisoning. Amines in general are difficult to analyze by Gas Chromatography (GC) due to their lack of volatility and their interaction with the GC column, often leading to significant tailing and poor reproducibility. Biogenic amines need to be derivatized before both GC and HPLC analyses. The objective of this research was to develop a relatively fast, reproducible method to derivatize and quantitate biogenic amines in fish at trace levels using GC/FID. The derivatizing reagent used in the experiments was propyl chloroformate, useful for aqueous samples. To confirm the identity of six derivatized biogenic amines GC/MS was used. To our knowledge no reference spectra for these derivatives has been published. It was concluded that best results are obtained using a Cold-On-Column (C.O.C.) inlet with a short column (15 meters), thick film stationary phase (ZB-5, 1.00μm df), and with recommendations to cut 40 cm from the inlet end of the column every 25 injections when using C.O.C. Duplicate samples of Atlantic Salmon were analyzed on days 0, 3, and 5. Levels of histamine were below 50 ppm for days 0 and 3, but day 5 showed average levels of 160 pm (cadaverine), 1000 ppm (histamine), and 350 ppm (tyramine). Good precision of six amine stardards at 50 ppm was shown: heptylamine 5.2%, putrescine 5.6%, cadaverine 5.0%, histamine 9.9%, tyramine 5.1%, and spermidine 6.2% RSD. / Master of Science

Title: Nitric oxide and its neurophysiologic role Objectives: The main aim of my diploma work is to evaluate the role of nitric oxide and its effects during epileptic seizure in rats. I summarize the present knowledge about nitric oxide and its effects on human organism in the theoretical section of this paper and I will suppose the positive effect of nitric oxide inhibitor in epileptic seizures in rats by the realization of my experiment. Methods: The experiment will be performed in the laboratory of Academy of Science of Czech Republic. Implementation will come through examining a set of ten rats. The first six will be given v (L-NPA) in an amount of 0,5mg to one side, which will take place by applying bilaterally to coele. Then after ten minutes 0,5µl of 4-aminopyridine (4-AP) will be applied bilaterally to coele. The control group, consisting of four rats will be given saline instead of L-NPA. The experiment will run for two days. Results: The course of epileptic seizure with application of L-NPA to examined group was compared with the control group. The experiment confirmed the positive effect of L-NPA in terms of delay and reduction of seizure. Keywords: nitric oxide, Nω -propyl-l-arginine, neurovascular coupling, 4-anopyridine, epilepsy

The clinically used antibiotic lincomycin consists of an amino-sugar and an amino-acid moiety. The incorporated amino-acid 4-propyl-L-prolin (PPL) is very important for the linomycin bioactivity, as evidenced by the lower activity of the related antibiotic celesticetin, which incorporates proteinogenic L-prolin instead. Gene clusters for the biosynthesis of both lincosamides are published and reflect a common basis - biosynthesis of amino-sugar precursor and condensation reactions. Additionally, in the biosynthetic gene cluster for lincomycin there is a sub-cluster of genes encoding the biosynthesis of PPL, the alkylated proline derivative (APD). PPL has a common biosynthetic origin with other APDs that are part of the structures of antitumor pyrrolobenzodiazepines and the signal molecule hormaomycin, which is also reflected in the presence of homologous genes in their gene clusters. The acquired knowledge on PPL biosynthesis thus can be applied to a larger group of natural products. The first overall concept of APD biosynthesis was published forty years ago. The milestone was the year 1995 when the gene cluster for lincomycin biosynthesis was published and specific gene products have been proposed for individual biosynthetic steps. The functional proof of proteins has been performed so far just...