by Qi Li. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves 192-199). / Acknowledgment --- p.i / Abstract --- p.ii / Table of Contents --- p.iii / Index of Componds --- p.iv / List of Tables --- p.v / List of Figures --- p.vi / Chapter 1. --- Introduction --- p.1 / Chapter 1.1. --- General Survey of Inclusion Chemistry --- p.1 / Chapter 1.2. --- The Importance of Hydrogen Bonds --- p.5 / Chapter 1.3. --- "Classical Inclusion Compounds of Urea, Thiourea and Selenourea" --- p.8 / Chapter 1.4. --- Research Strategy --- p.12 / Chapter 2. --- Description of Crystal Structures --- p.16 / Chapter 2.1. --- Urea-Anion Inclusion Compounds --- p.16 / Chapter 2.1.1. --- Halide complexes --- p.18 / Chapter 2.1.2. --- Bicarbonate complexes --- p.30 / Chapter 2.1.3. --- Allophanate complexes --- p.36 / Chapter 2.1.4. --- Borate and pentaborate complexes --- p.44 / Chapter 2.1.5. --- Complex featuring both host-host and host-guest hydrogen bonding --- p.60 / Chapter 2.1.6. --- Tetraethylammonium and phosphonium chloride complexes --- p.65 / Chapter 2.2. --- Thiourea-Anion Inclusion Compounds --- p.71 / Chapter 2.2.1. --- Halide Complexes --- p.73 / Chapter 2.2.2. --- Bicarbonate Complexes --- p.76 / Chapter 2.2.3. --- Nitrate Complexes --- p.87 / Chapter 2.2.4. --- Formate Complexes --- p.101 / Chapter 2.2.5. --- Acetate Complexes --- p.113 / Chapter 2.2.6. --- Oxalate and Fumarate Complexes --- p.127 / Chapter 2.2.7. --- Unsymmetrical quaternary ammonium ions as guests --- p.138 / Chapter 2.3. --- Selenourea-Anion Inclusion Compounds --- p.152 / Chapter 3. --- Summary and Discussion --- p.161 / Chapter 3.1. --- Structural Features and Relationships --- p.161 / Chapter 3.2. --- Hydrogen Bonding in Urea/Thiourea/Selenourea-Anion Inclusion Compounds --- p.164 / Chapter 3.3. --- Linkage Modes of Urea and Thiourea Molecules --- p.168 / Chapter 3.4. --- Comolecular Aggregates of Urea and Other Host Components --- p.173 / Chapter 3.5. --- Comolecular Aggregates of Thiourea and Other Host Components --- p.175 / Chapter 4. --- Experimental --- p.177 / Chapter 4.1. --- Preparation --- p.177 / Chapter 4.2. --- Crystallography --- p.182 / Chapter 5. --- References --- p.192 / Appendix A: Tables of Atomic coordinates and thermal parameters --- p.200 / Appendix B: Publication Based on Results Reported in This Thesis --- p.243

No description available.

Thesis (Ph.D.)--Auburn University, 2005. / Abstract. Vita. Includes bibliographic references.

Thesis (M. S.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Spyros G. Pavlostathis; Committee Member: Ching-Hua Huang; Committee Member: John A. Pierson.

The availability and assimilation of NH₄⁺ plays an integral role in the growth of microorganisms and the production of amino acids by these organisms. This study investigated the dissociation of NH₄⁺in aqueous solution, its availability and effect on the enzymes of NH₄⁺ assimilation and its influence on lysine production by Corynebacterium glutamicum.In aqueous solution the extent of dissociation of NH₄C1, {NH₄)₂S0₄ and (NH₄)₂HP0₄ increases with decreasing concentration. A model is proposed for the dissociation of these molecules. It is believed that at very low concentrations, dissociation to NH₃ plus the respective counter-ions occurs. At these low concentrations the NH₃ acts as the substrate for glutamine synthetase. At the higher concentrations dissociation is to NH₄⁺ which is the substrate for glutamate dehydrogenase. At these higher concentrations the enzyme activities obtained for glutamate dehydrogenase, at equivalent concentrations of the above ammonium salts, were different when based on the total concentration of NH₄⁺, and similar when based on the concentration of free NH₄⁺. L-Iysine occurs in the +1 ionic form, at pH 7,2. The lysine which is produced during fermentation associates with the anionic counter-ion of the ammonium salt used. The concentration of the free NH₄⁺ in the media appears to affect both the rate of lysine synthesis as well as the yield. The lysine fermentation occurs in two stages; a growth (or replicative) phase, during which very little lysine is produced, and a lysine synthesis (or maturation) phase. During the lysine synthesis phase there is no cell replication, however an increase in the mass of the biomass produced is apparent. Evidence is provided for the possible concomitant synthesis of the the cell wall polymer, glycerol teichoic acid, and lysine. On the basis of this evidence, a nucleotide balance is proposed for lysine and teichoic acid synthesis. The replicative phase and the maturation phase have to be effectively separated to obtain optimal lysine yields and titres. It is believed that teichoic acid synthesis during the replicative phase must be kept to a minimum for optimal yields and titres to be obtained, and on completion of the cell wall and therefore teichoic acid synthesis, lysine synthesis ceases. As the production of lysine appears to be affected by the NH₄⁺ concentration in the culture media, it is proposed that a futile cycle may exist around the transport and assimilation of the NH₄⁺. If the fermentations are run at low free NH₄⁺ concentrations, it was shown that lysine yields of 0,66, on the glucose utilised, are attainable during the fermentation.

by Cheng Sau Wan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1996. / Includes bibliographical references (leaves [72]-[76]). / TABLE OF CONTENTS --- p.i / ABSTRACT --- p.iv / LIST OF FIGURES --- p.vi / LIST OF TABLES --- p.x / Chapter CHAPTER ONE --- RESEARCH BACKGROUND --- p.1 / Chapter 1.1 --- Introduction --- p.1 / Chapter 1.2 --- Matrix-assisted laser desorption / ionization mass spectrometry (MALDI) --- p.2 / Chapter 1.2.1 --- Laser desorption methods --- p.2 / Chapter 1.2.2 --- The matrix --- p.3 / Chapter 1.2.2.1 --- Role of the matrix --- p.3 / Chapter 1.2.2.2 --- Features of the matrix --- p.4 / Chapter 1.2.3 --- Mechanisms of ion formation --- p.6 / Chapter 1.2.3.1 --- Desorption process(es) --- p.6 / Chapter 1.2.3.2 --- Ionization process(es) --- p.7 / Chapter 1.3 --- Sequencing of DNA --- p.8 / Chapter 1.3.1 --- DNA sequencing procedure --- p.10 / Chapter 1.3.1.1 --- Generation of the nested set of DNA molecules --- p.11 / Chapter 1.3.1.2 --- Sequence analysis --- p.11 / Chapter 1.3.2 --- MALDI-TOF-MS as a DNA sequencing tool --- p.12 / Chapter 1.3.3 --- MALDI analysis of oligonucleotides --- p.14 / Chapter 1.4 --- Outline of the present work --- p.16 / Chapter CHAPTER TWO --- INSTRUMENTATION AND EXPERIMENTAL --- p.18 / Chapter 2.1 --- Time-of-flight mass spectrometry (TOF-MS) --- p.18 / Chapter 2.1.1 --- Linear time-of-flight mass spectrometry --- p.18 / Chapter 2.1.2 --- Reflectron time-of-flight mass spectrometry --- p.21 / Chapter 2.1.3 --- Ion detection --- p.22 / Chapter 2.1.4 --- Vacuum system --- p.22 / Chapter 2.2 --- Instrumentation --- p.24 / Chapter 2.2.1 --- The laser system --- p.24 / Chapter 2.2.2 --- Ion source and vacuum system --- p.24 / Chapter 2.2.3 --- Flight tube and reflector --- p.27 / Chapter 2.2.4 --- The detector --- p.28 / Chapter 2.2.5 --- Data acquisition and computer control --- p.28 / Chapter 2.3 --- Experimental --- p.29 / Chapter 2.3.1 --- Sample preparation --- p.29 / Chapter 2.3.2 --- Mass spectrometric analysis --- p.30 / Chapter CHAPTER THREE --- USE OF AMMONIUM SALTS AS CO-MATRICES --- p.32 / Chapter 3.1 --- Introduction --- p.32 / Chapter 3.2 --- Experimental --- p.35 / Chapter 3.3 --- Results and Discussion --- p.36 / Chapter 3.3.1 --- Effects of counter-anions --- p.36 / Chapter 3.3.2 --- Effects of matrix materials --- p.40 / Chapter 3.4 --- Conclusions --- p.43 / Chapter CHAPTER FOUR --- USE OF POTASSIUM SALTS AS CO-MATRICES --- p.44 / Chapter 4.1 --- Introduction --- p.44 / Chapter 4.2 --- Experimental --- p.44 / Chapter 4.3 --- Results and Discussion --- p.44 / Chapter 4.3.1 --- Adduct formation --- p.49 / Chapter 4.3.2 --- Signal enhancement --- p.50 / Chapter 4.4 --- Conclusions --- p.52 / Chapter CHAPTER FIVE --- ANALYSIS OF HIGH MASS OLIGONUCLEOTIDES --- p.53 / Chapter 5.1 --- Introduction --- p.53 / Chapter 5.2 --- Experimental --- p.53 / Chapter 5.3 --- Results and Discussion --- p.54 / Chapter 5.4 --- Conclusions --- p.67 / Chapter CHAPTER SIX --- CONCLUSIONS AND FURTHER WORK --- p.68 / Chapter 6.1 --- Conclusions --- p.68 / Chapter 6.2 --- Further work --- p.70 / ACKNOWLEDGMENT --- p.A1 / REFERENCES --- p.R1 - R5

The theoretical model of Beratan and Onuchic predicts a large attenuation of ET rates through hydrogen bonds; however, the effect of individual hydrogen bond on electron transfer reaction has not been systematically studied. The organic complexes in this study are a series of crown ether/ammonium salt, which incorporate a redox partner on each component of the complex. The dimethoxynaphthalene redox donor was attached to the crown ether and a series of ammonium salts was synthesized which bear substituted quinone and naphthoquinone acceptor. The complexes characterization and preliminary electron transfer rate measurement were completed with UV/Vis and steady-state emission spectroscopy.

Sigma receptors originally thought to be an opioid receptor is now categorized as a distinct class of receptor. There are two main subtypes, the sigma-1 receptor and an uncharacterised binding site, named the sigma-2 binding site. The presence of the sigma-2 binding site shows high correlation with proliferation of cells and is associated with cancer. I have categorized sigma-1 and sigma-2 binding sites in 11 human tumour cell lines. I have demonstrated that tumour cell lines from a range of tissues express both sigma-1 and sigma-2 binding sites. One exception is the MCF7 breast cancer cell line, which lacks sigma-1 receptors. I show that the quantitation of sigma-2 binding sites using the "masking" protocols are flawed, significantly overestimating levels of sigma-2 binding sites. I propose novel protocols to determine levels of sigma-1 receptors and sigma-2 binding sites in cell lines and tissue. Using radioligand binding assays in MCF7 cells, I have characterised novel sigma-2 ligands. These ligands are simple ammonium salts containing a single nitrogen atom. They are simpler than the previously recognised pharmacophore for the sigma-2 site. I have shown that these simple ammonium salts show graded affinity for the sigma-2 binding site. The highest affinity ligands were dihexylammonium (pKi 7.58) and dioctylammonium (pKi 7.9). I have used these ammonium salts and previously characterised ligands to determine sigma-2 binding site biology. I have shown that the biological activity of these drugs is related neither to their hydrophobicity nor their ability to effect calcium signalling in cells. I propose that the Hill slope of binding is inversely related to the efficacy of a ligand to inhibit metabolic activity of cancer cells. Furthermore, I offer an explanation as to why concentrations of sigma-2 ligands far higher than their determined binding affinities are required to inhibit metabolic activity.

In this work, electrolytes for secondary batteries and fuel cells were investigated. Ionic liquids (ILs), for use as battery electrolytes, were formed using quaternary ammonium salts (Quats) and aluminum chloride. The room temperature (RT) carbonate fuel cell was demonstrated by modifying a commercially available anion exchange membrane, utilizing positive quaternary ammonium fixed sites, to transport carbonate. The charge density on the nitrogen and the symmetry of the Quat were demonstrated to be the dominant factors in determining the IL melting point (MP). The introduction of a benzyl ring was found to lower the MP of the ILs by increasing the size of the Quat, while disrupting its symmetry. ILs formed from asymmetric quaternary ammonium salts having three distinct groups were found to have lower melting points than those formed using Quats with two groups. Replacement of an alkyl group with a rigid ether linkage can lower the IL melting point. Assymetric alkyl substituted Quats were found to form more electrochemically stable, less viscous ILs than their benzyl substituted counterparts. The increased electrochemical stability is due to the smaller butyl chain being a worse leaving group than the benzyl group. Similarly, the smaller size of the alkyl substituted Quats results in the lower viscosities. Lithium and sodium can be reversibly deposited from neutral ILs following the addition of an additive (such as SOCl2). The additive disrupts the strong coordination between Na+, or Li+, and AlCl4-. Chlorinated compounds, such as chloroform-D and carbon tetrachloride, were demonstrated to catalyze the reversible reduction of sodium. When neutralized with lithium and sodium, reversible Li-Na alloys were deposited. The Li-Na alloy appears to suppress dendrite formation and could potentially be used as a metal based anode in a rechargeable Li battery. A novel room temperature carbonate fuel cell was constructed. The alkaline environment could eliminate the need for water in the oxidation of methanol. Cells were operated on hydrogen, 1M methanol, and pure methanol fuels. CO2 was produced at the anode and O2 and CO2 were necessary at the cathode for operation, indicating that carbonate was the conducting ion.

Quaternary ammonium compounds (QACs) are widely used in commercial and consumer applications as disinfectants, fabric softeners, hair conditioners, and emulsifying agents. The massive production and utilization of QACs has led to their extensive discharge into the environment, raising concerns globally. Several studies have reported on potential risks and detrimental effects of QACs on the natural environment and public wastewater treatment plants. Biological treatment has been found to be an effective way to remove QACs and especially aerobic treatment processes can provide rapid biodegradation via a consortium of bacteria. Although extensive research has been conducted on the fate and effect of QACs, relatively little is known about their effect on aerobic biological treatment processes, especially on nitrification. Research was conducted on the fate and effect of alkyl benzyl dimethyl ammonium chloride (AB), a QAC widely used as disinfectant, in mixed aerobic and nitrifying cultures. The results of this study demonstrated that up to 50 mg/L AB was efficiently degraded in a mixed aerobic culture fed with dextrin and peptone, although trace residual AB levels were observed. Nitrification of the produced ammonia was complete at an AB concentration of 20 mg/L after an acclimation period, but was almost completely inhibited at 50 mg/L. Mixed aerobic cultures maintained only with AB as external nitrogen and carbon source achieved a high degree of AB degradation at both 20 and 50 mg/L. Ammonia oxidation by a nitrifying culture, enriched with ammonium chloride and sodium bicarbonate, was inhibited with increasing AB concentration and completely ceased at 15 mg/L AB. Degradation or utilization of AB was not observed for all tested AB concentrations between 2 to 20 mg/L. Based on these experimental results, and assuming non-competitive inhibition, a relatively low value of the AB inhibition coefficient was obtained, which indicates a relatively high susceptibility of the ammonia oxidizers to AB. The results of this study have significant implications for both engineered and natural systems relative to the fate and effect of QACs.