Electrochemical reduction of fluorinated systems and derived chemistry

The work described in this thesis is divided into four sections:1. The electrochemical reduction of fluorocarbon derivatives has been investigated. A number of systems have been studied analytically (using cyclic volt amine try) ; whilst preparatively a range of compounds have been synthesised, including semi-conducting polymers and four-memberedperfluorocyclic products. 2. The use of sodium amalgam as an electromimetic medium to facilitate reduction of various fluorocarbon substrates has been studied. A series of volatile cyclic and acyclic F-dienes have been prepared from F-alkenes in good yield and conversion. The chemistry of these F-dienes is then described: 3. Both mono- and bi- functional nucleophiles have been reacted, giving a range of novel substitution products. 4. A number of free radical and cycloaddition reactions have been attempted without success. However, the complexation of decamethylferrocene as a metallocene one electron donor, with various F-alkenes of low reduction potential, has allowed a radical anion of a perfluorocyclic-diene to be stabilized and fully characterized for the first time

Unified Chew-Mandelstam SAID analysis of pion photoproduction data

A unified description of single-pion photoproduction data, together with pion- and eta-hadroproduction data, has been achieved in a Chew-Mandelstam parametrization which is consistent with unitarity at the two-body level. Energy-dependent and single-energy partial wave analyses of pion photoproduction data have been performed and compared to previous SAID fits and multipoles from the Mainz and Bonn-Gatchina groups.Comment: 11 pages, 9 figures, and 2 table

The relatinship between refractive error and physical fatigue

The purpose of this study was to determine what type of refractive shift, if any, would occur as the result of enduring extreme physical fatigue. One hundred twenty-four marathon runners, and ten control subjects were measured with autorefractors before and immediately after the 26.2 mile Seattle marathon on November 27, 1993. The authors hypothesized that a significant shift in equivalent sphere toward hyperopia would occur due to the effects of dehydration, sympathetic activation, and possible loss of ciliary muscle tonus. The results indicate that there is no significant shift in refraction when compared to the controls, but individual subjects exhibited clinically relevant hyperopic or myopic shifts. Contact lens wearing subjects showed a statistically significant shift in refractive error towards myopia when compared to non-contact lens wearing subjects

Identification of a Phytotoxic Fungus and an Investigation into the Isolation of its Phytotoxic Constituents

A fungus was isolated from Hedera helix (English ivy) leaves experiencing necrosis and identified as Diaporthe eres by molecular techniques. The fungus was grown in potato dextrose broth medium and the culture medium was extracted with ethyl acetate. Bioassay guided fractionation of ethyl acetate extract of culture filtrate of this fungus led to the isolation of two phytotoxic compounds that are active against the seed germination of the monocotyledon Agrostis stolonifera at 1 mg mL-1. Structures of these active compounds were determined by spectroscopic methods and were determined 8-hydroxy-3.7-dimethylisochroman-1-one and 2-(4-hydroxyphenyl)-ethanol. This is the first finding presented on the phytotoxic effects of as 8-hydroxy-3.7-dimethylisochroman-1-one

Physics Opportunities with Meson Beams

Over the past two decades, meson photo- and electro-production data of unprecedented quality and quantity have been measured at electromagnetic facilities worldwide. By contrast, the meson-beam data for the same hadronic final states are mostly outdated and largely of poor quality, or even nonexistent, and thus provide inadequate input to help interpret, analyze, and exploit the full potential of the new electromagnetic data. To reap the full benefit of the high-precision electromagnetic data, new high-statistics data from measurements with meson beams, with good angle and energy coverage for a wide range of reactions, are critically needed to advance our knowledge in baryon and meson spectroscopy and other related areas of hadron physics. To address this situation, a state of-the-art meson-beam facility needs to be constructed. The present paper summarizes unresolved issues in hadron physics and outlines the vast opportunities and advances that only become possible with such a facility.Comment: 46 pages, 10 figures, 4 table

Mjerenja u JLab s realnim fotonima pomoću fotonskog označivača u dvorani B

Data on real-photon induced reactions have been taken using the Tagged Photon Facility (TPF) and the Continuous Electron Beam Accelerator Facility (CEBAF) at the Thomas Jefferson National Accelerator Facility (JLab) during the first year of running in Hall B. These data have been taken for the purpose of investigating the electromagnetic structure of mesons, nucleons, and nuclei. This report summarizes the status of these experiments.Tijekom prve godine rada sustava s označavanjem fotona u dvorani B pri ubrzivaču s neprekidnim elektronskim snopom (CEBAF) u Thomas Jeffersonovom nationalnom akceleratorskom pogonu (JLab) postigli su se podaci o raznim fotonima izazvanim reakcijama. Tim se podacima istražuju elektromagnetske strukture mezona, nukleona i atomskih jezgri. Ovaj je rad sažetak tih mjerenja

Experimental Tests of QCD Scaling Laws at Large Momentum Transfer in Exclusive Light-Meson Photoproduction

We evaluated CLAS Collaboration measurements for the 90◦ meson photoproduction off the nucleon using a tagged photon beam spanning the energy interval s = 3–11 GeV2. The results are compared with the “quark counting rules” predictions