<p>Tropospheric fine particulate matter (PM) poses serious health risks and has a significant impact on global climate change. The measurement of various aspects of PM is challenging due to its complex chemical nature. This dissertation addresses various aspects of PM, including composition, measurement, and visibility. The U.S. Environmental Protection Agency (EPA) proposed a new secondary standard based on visibility in urban areas using 24-h averaged measurements of either light scatter or PM concentration. However shorter averaging times may better represent human perception of visibility. Data from two studies conducted in Lindon, UT, 2012, and Rubidoux, CA, 2003, were used to compare different techniques to estimate visibility, particularly the effect of relative humidity on visibility estimations. Particle composition was measured in Salt Lake City during January-February of 2009. One-hour averaged concentrations of several gas phase and particle phase inorganic species were measured. The results indicate ammonium nitrate averages 40% of the total PM2.5 mass in the absence of inversions and up to 69% during strong inversions. Also, the formation of ammonium nitrate is nitric acid limited, while the formation of ozone appears to be oxidant and volatile organic carbon (VOC) limited. Reduction of NOx will reduce ammonium nitrate secondary particle formation, however, a decrease in NOx may increase ozone concentration. </p><p> Due to the complexity of PM it is poorly characterized. A large fraction of PM is composed of organic compounds, but these compounds are not regularly monitored due to limitations in current sampling techniques. The GC-MS Organic Aerosol Monitor (OAM) combines a collection device with thermal desorption, gas chromatography and mass spectrometry to quantitatively measure the carbonaceous components of PM on an hourly averaged basis. A compact GC and simple pre-concentrator were developed for the system to decouple separation from manual injection and enhance separation of environmentally-relevant polar organic compounds, such as levoglucosan. The GC-MS OAM is fully automated and has been successfully deployed in the field. It uses a chemically deactivated filter for collection followed by thermal desorption and GC-MS analysis. Laboratory tests show that detection limits range from 0.2 to 3 ng for many atmospherically relevant compounds. The GC-MS OAM was deployed in the field for semi-continuous measurement of the organic markers, levoglucosan, dehydroabietic acid, and several polycyclic aromatic hydrocarbons (PAHs) during winter (January to March), 2015 and 2016. Results illustrate the significance of this monitoring technique to more fully characterize the organic components of PM and identify sources of pollution. </p><p> Keywords: air pollution, fine particulate matter, PM_2.5, secondary organic aerosol, organic markers, levoglucosan, PMF. </p>

<p> Doped semiconductor quantum dots (QDs) comprise an important subclass of nanomaterials in which a small quantity of impurity is added intentionally, adding another degree of freedom to alter their size-dependent physical and electronic properties. Intense, tunable, long lived and stable photoluminescence make them quintessential candidates for many opto-electronic applications including solid-state lighting, display devices and biomedical imaging. ZnSe QDs, which are blue-emitting fluorophores, were doped with Cu⁺¹ to redshift their photoluminescence (PL) to green region of the visible spectrum. These Cu-doped ZnSe QDs were then codoped with Al³⁺, Ga³⁺ and In³⁺ to improve the PL quantum yield (QY) by eliminating the defect states originating from charge imbalance created by aliovalent doping. Codoping also resulted in further redshifting of the PL, covering most of the visible spectrum, making them potential candidates for use in solid-state lighting and as optical down converters in next generation light emitting diodes (LEDs). To better understand the optical properties of these materials, local structure around the luminescent centers was investigated by extended X-ray absorption fine structure (EXAFS). Cu was found to occupy a distorted tetrahedral site with the codopant residing in a substitutional Zn site. Based on the structural information obtained by EXAFS, density functional theory calculations (DFT) were performed to get a clear picture of the energy levels associated with the electronic transitions. Furthermore, the dynamics studies of the exciton and charge carriers were carried out to get deeper insight of the various photophysical processes involved. The fluorescence lifetime was increased approximately 10 times after doping. </p><p> The multielectron catalytic reactions often involve multimetallic clusters, where the reaction is controlled by the electronic and spin coupling between metals and ligands to facilitate charge transfer, bond formation/breaking, substrate binding, and release of products. A method was developed to detect X-ray emission signal from multiple elements simultaneously to probe the electronic structure and sequential chemistry that occurs between the elements. A wavelength dispersive spectrometer based on the von-Hamos geometry was used, that disperses K&beta; emission signals of multiple elements onto an area detector, and enables an XES spectrum to be measured in a single-shot mode. This overcomes the scanning needs of the Rowland circle spectrometers, and the data is free from temporal and normalization errors, and therefore ideal to follow sequential chemistry at multiple sites. This method was applied to MnO_x based electrocatalysts, and the effect of Ni addition was investigated. Electro-deposited Mn oxide catalyses oxygen-evolution reaction (OER) and oxygen-reduction reaction (ORR) at different electrochemical potentials under alkaline condition. Incorporation of Ni reduced the low valent Mn component resulting in higher average oxidation state of Mn in MnNiOx under ORR and OER conditions, when compared to MnO_x under similar conditions. The reversibility of the electrocatalyst was also found to improve by the inclusion of Ni.</p>

<p> Human biomonitoring is an analytical challenge to find environmental organic chemicals of varying polarity, persistency, and potential toxicity in a suitable, ideally non-invasive matrix at ppb levels that are significantly above method blanks. Compared with more traditional matrices of adipose tissue, serum, and urine, toenail clippings samples are non-invasive, compact, can be shipped without refrigeration, stored indefinitely at room temperature, and processed without concerns for biohazards. With both hydrophilic and hydrophobic layers, toenails contain 1-2% lipid, which is several times higher than serum. Toenails grow slowly and are trimmed every 2-3 months, which offers the potential to integrate both chronic and pulsed episodic exposures. Using toenail samples (65 to 340 mg) donated from four individuals and an indoor house cat, the hypothesis that toenails are a suitable biomonitoring matrix was tested by analyzing for persistent pesticides, over 50 PCB congeners, moderately persistent PBDEs, and transient compounds of triclosan and bisphenol A by using GC/High Resolution MS (GC/HRMS) analysis and for unsuspected compounds using GC/full scan MS. Although not fully digested and dissolved, toenails averaged 1.22% lipid (sd 0.20%, n=10). Lipid was separated and determined using a new small single-use 2-g S-X3 gel permeation chromatography flash column with high purity nitrogen. Multiple toenail samples from one individual were collected for over a year for replicate analysis, p,p&rsquo;- DDE averaged 0.82 ng/g-nail, sd 0.28, n=5 and 65.2 ng/g-lipid, sd 15.3, n=5 on lipid-adjusted basis. <i>Trans</i>-nonachlor averaged 3.08 ng/g-nail, sd 1.03, n=5; mean 254 ng/g-lipid, sd 97, n=5. PBDE 28 averaged 0.29 ng/g-nail, sd 0.10, n=5; mean 24.8 ng/g-lipid, sd 13.3, n=5. PBDE 85 averaged 0.25 ng/g-nail, sd 0.06, n=5; mean 20.8 ng/g-lipid, sd 6.2, n=5. PBDE 153 averaged 1.82 ng/g-nail, sd 0.51, n=6; mean 150 ng/g-lipid, sd 49.3, n=6. Most effectively biomonitored in toenails were normally transient triclosan (mean 58.3 ng/g-nail, sd 6.6, n=2), chlordanes, DDT, PBDEs, and PCBs including congeners with 2,5- or 2,3,6-chlorine substitution (PCBs 52, 49, 44, 70, 95, 101, 87, and 110), which are suspect neurotoxins, but are rarely found in extant serum biomonitoring data. Toenail soap wash samples indicated little (&lt; 4%) or no exogenous contamination, except for the musks galaxolide and tonalide in most samples, which ranged up to 30%, likely from topical application. The one cat toenail sample had elevated concentrations of PBDEs and especially chlordanes. Unsuspected tentatively identified compounds included a UV Filter compound, octocrylene, a hydroxyl-methyl benzothiazole, and several compounds used in flavors or fragrances.</p><p>

<p> Mass spectrometry (MS) is an efficient analytical tool due to a number of advantages for providing high sensitivity, high-throughput analysis and less sample consumption. Since 1897, MS has continued to evolve and significant developments have occurred in the area of ionization techniques. Since 2010, inlet ionization techniques have shown the potential to compete in the areas of sensitivity and sample conservation with electrospray ionization (ESI) and matrix assisted laser desorption/ionization (MALDI). Matrix assisted inlet ionization (MAI) produces multiply charged ions within a mass spectrometer inlet without the need of high voltage, a laser or nebulizing gas. For MAI, sample preparation can be critical affecting the sensitivity, reproducibility and carry over. This dissertation presents new sample preparation techniques which have shown substantial improvement in sensitivity and reproducibility. The limit of detection can be achieved to less than 50 amol with the new sample preparation technique. Furthermore, this new sample introduction process enhance matrix assisted ionization (MAI) and solvent assisted ionization (SAI)&rsquo;s ability to couple with Thin-layer chromatography.</p><p>

<p> This dissertation details original work focused on the DNA adduct N2-(1-carboxyethyl)-2'-deoxyguanosine (CEdG). This DNA adduct results from the spontaneous reaction of DNA with the endogenous and exogenous formed, carbohydrate-derived, reactive carbonyl species, methylglyoxal. Using <i>in vitro</i> steady state kinetics, we have shown that CEdG in template DNA leads to DNA miscoding effects when the model replicative polymerase, exonuclease-free Klenow fragment (KF-) is used. The development, validation and application of a novel stable isotope dilution, triple quadrupole mass spectrometric method for the quantitation of CEdG is also detailed. This method was used to quantitate CEdG in urine from diabetic rats, urine from human patients, human tumor and adjacent biopsy tissue, diabetic animal tissue and DNA treated with methylglyoxal. Finally, we detail the adaptation, validation and application of a novel, commercially-available microfluidic HPLC-chip for increased sensitivity in the quantitation of CEdG and also apply it to the quantitation of the RNA analogue, CEG. Combined, these studies establish CEdG as a potential biomarker for glycation and point to a viable avenue for connecting chronic glycolytic flux with genetic instability. </p>

<p> Many recent efforts in the field of microfluidics have been focused on reducing the size and the complexity of devices and on simplifying the methods of analysis performed with them. Gradient elution moving boundary electrophoresis (GEMBE) is a recently described counterflow electrophoresis method that was developed to simplify the analysis of ions in complex matrices. In this thesis, the improvement of the limit of detection of GEMBE and reduction of the GEMBE channel length is investigated. </p><p> Integration of simple and robust device components required for the successful adaptation of many analytical methods to multiplexed and field-portable devices often has negative effects on detection sensitivity, such as in the optical detection components in a capillary electrophoresis (CE) system. One of the simplest methods to improve sensitivity in the CE field is known as sample stacking. This method involves preparing the sample in a buffer with a different concentration (and conductivity) than that of the run buffer, such that when an electric field is applied the analyte concentration is increased at the boundary between the two different buffer concentrations. A method in which the sample is prepared in a buffer at a lower concentration than the run buffer has been implemented. This method achieves a significantly greater signal enhancement than expected for sample stacking. The concentration enhancement ability of this method is demonstrated utilizing GEMBE with channel current detection. </p><p> Current GEMBE device construction methods impose limitations on the minimum length of the separation channel. One technique well suited for minimizing the size of the GEMBE separation channel is multiphoton absorption polymerization (MAP). Because MAP is a non-linear optical fabrication method, polymerization is limited to a small region near the focal point of a laser beam. As a result, three-dimensional structures with small feature sizes can be easily created. The 3D capabilities of MAP have been exploited to create channels with circular cross sections and &sim;300 &mgr;m lengths for GEMBE. The integration of device components fabricated with MAP and molded with PMDS allows visualization of the GEMBE separations, and provides insights into the effect of channel length on GEMBE step width.</p>

Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2007. / Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 5919. Adviser: Milos V. Novotny. Title from dissertation home page (viewed May 9, 2008).

Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2007. / Source: Dissertation Abstracts International, Volume: 68-09, Section: B, page: 5918. Adviser: David E. Clemmer. Title from dissertation home page (viewed May 12, 2008).

Thesis (Ph. D.)--Indiana University, Dept. of Chemistry, 2008. / Title from PDF t.p. (viewed May 13, 2009). Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4721. Adviser: James P. Reilly.

Thesis (Ph. D.)--University of Illinois at Urbana-Champaign, 2007. / Source: Dissertation Abstracts International, Volume: 68-07, Section: B, page: 4441. Adviser: Jonathan V. Sweedler. Includes bibliographical references. Available on microfilm from Pro Quest Information and Learning.