Thesis (M.S.)--Ohio University, Novmeber, 1999. / Title from PDF t.p.

Thesis (Ph. D.)--University of Hong Kong, 1993.

Thesis (Ph. D.)--Johns Hopkins University, 1924. / Vita.

Nitrogen oxides control the global formation of ozone in the lower atmosphere and influence the much higher levels of ozone formed in areas subjected to photochemical air pollution. As an important member of the nitrogen oxide family, N02 plays a significant role in serving as the only known source of ozone (through photolysis) in the lower atmosphere and as sink for HO via the formation of nitric acid. Ozone can be destroyed by reaction with another member of the nitrogen oxide family, nitric oxide (NO), to reform N02. This cycle between NO, N02 and 03 is known as the NOx-03 photostationary state (PSS). Imbalances in this cycle have been used to calculate ambient levels of oxidants (such as R02 and H02) responsible for ozone production. Consequently, accurate N02 measurements are critical to making meaningful measurements of the imbalances in the NOx-03 photostationary states (PSS). A low pressure laser-excited fluorescence technique (FAGE) for the direct determination of atmospheric N02 has been developed. This technique has been explored with both a Nd-YAG laser (1.4 W, 532nm, 30Hz) and a Cu-vapor (1.2 W, 511nm, 5.6kHz) laser. The detection limits for these instruments, under laboratory conditions and a signal collection time of 20s (lOs each signal and background), have been determined to be 450 and 350pptv N02, respectively. In these systems, the background was measured by chemically reducing N02 with FeS04°7H20. Ambient measurements of the NOx-03 photostationary state (PSS) were undertaken on a rooftop monitoring site in downtown Portland, Oregon. N02 was monitored with the Cu-vapor system. Nitric oxide and ozone were monitored with standard instruments. Data for three days in 1990 are presented. Overall these data sets clearly show that despite daily changes in concentration of NO, N02 and 0 3 of factors of 4-10 each, the PSS remains relatively constant to within -50%. This is in itself strong confIrmation of the primary importance of the NOx-03 photo stationary state in controlling the concentrations of these species at these levels. In addition, these experiments also serve to demonstrate that the monitoring instruments, including FAGE-N02, are not subject to serious interferences or artifacts at these concentration levels.

No description available.

No description available.

Vita. / Digitized by Kansas Correctional Industries

Nitric oxide (NO) has been shown to both suppress and promote tumor growth, depending in part on concentration. Exogenous delivery of NO may lead to tumor suppression. Recent studies have proposed ruthenium nitrosyl complexes as catalytic donors of NO in reductive environments. Catalytic donation can provide a long-term, elevated NO flux compared to single use donors. Site-specific delivery is desirable to reduce systemic side effects, such as lowering of blood pressure. Three new ruthenium nitrosyl complexes were synthesized to impart site-specificity through amide coupling to polymers, silica nanoparticles, iron oxide nanoparticles and antibodies. The catalytic activity of new and existing compounds was then assessed. However, upon one-electron reduction of ruthenium nitrosyl complexes, insignificant amounts of NO were detected, suggesting an alternative mechanism than that proposed in prior reports. The mechanism of [Ru(EDTA)NO]²⁻ decay was more thoroughly analyzed. Spectrophotometric decay of [Ru(EDTA)NO]²⁻ indicates that one or multiple nitrogen oxide species are released. Previous studies have suggested a disproportionation mechanism leading to the generation of more highly reduced species such as N₂ and NH₄⁺. Experiments were designed to analyze possible decomposition products such as [Ru(EDTA)NO]⁻ and [Ru(EDTA)H₂O]²⁻. A disproportionation mechanism was determined likely. Decomposition of [Ru(EDTA)NO]²⁻ was also observable following reductive nitrosylation of [Ru(EDTA)H₂O]⁻ in the presence of HNO. The decomposition product, [Ru(EDTA)H₂O]²⁻, was observed through the binding of pyrazine (pz) or dipyridine (bipy) and formation of [Ru(EDTA)pz]²⁻ or [Ru(EDTA)bipy]³⁻. Formation of [Ru(EDTA)bipy]³⁻ or [Ru(EDTA)pz]²⁻ via reductive nitrosylation of [Ru(EDTA)H₂O]⁻ also provides an indirect method of HNO detection that is selective from NO.

No description available.

The deposition of atmospheric nitrogen is now recognized as a major driver of biodiversity changes at mid to high latitudes. It has previously been shown that regional variations in wet nitrogen deposition in the British Isles are reflected in broad targeted chemical parameters in the common heathland lichen Cladonia portentosa. A more detail analysis of alterations in the metabolic pathways in Cladonia portentosa collected from different locations within the UK was undertaken by applying the environmental metabolomics approach. Fourier transform infrared spectroscopy (FTIR) and liquid chromatography mass spectrometry (LC-MS) were applied in combination with principal component analysis (PCA) and partial least squares regression analysis (PLSR). The latter statistical method was used to correlate measured variables with modelled atmospheric data including wet nitrogen deposition, nitrogen concentration and precipitation. While FTIR in combination with PCA and PLSR revealed signatures of broad metabolic classes, LC-MS in combination with PCA and PLSR allowed the identification of betaine lipids (BL) as potential biomarkers of nitrogen enrichment. A compound tentatively identified as monoacylglycerol-(N,N,N trimethyl)-homoserine (MGTS) showed the strongest positive relation to increasing wet nitrogen deposition regimes and consequent phosphorus deficiency. In contrast, the structurally related phosphatidylcholine containing a C18:2 ester showed the opposite trend in natural populations of C. portentosa. Results obtained for C. portentosa collected from the N manipulation site Whim Moss indicated that ammonium is causal for the increase of two of the identified betaine lipids in natural populations in C. portentosa. Betaine lipids as well as the phosphatidylcholine biomarker could potentially be used to monitor nitrogen regimes and resulting phosphorus limitation on the lichen C. portentosa. The approach used for this study represented an effective integration of the complementary analytical techniques of FTIR and LC-MS in combination with multivariate statistical tools for environmental metabolomic studies.