The radial heterogeneity of some columns used in high performance liquid chromatography (HPLC) was investigated using an on-column microelectrochemical amperometric detector. Such a detector allowed the recording of the elution profiles at different spatial positions throughout the column exit cross-section. From this, we obtain information about the radial distribution of the mobile phase velocity, column efficiency, and analyte concentration. In all cases, the results obtained show that the spatial distribution of the mobile phase velocity does not follow a piston-flow behavior but exhibits radial heterogeneity with differences not exceeding 5% between the center and wall regions of any column. The efficiency was found to be lower in the wall region of the column than in its core region (the central core with a radius of 1/3 the column inner radius) by up to 40-50% in some columns. The radial distribution of the maximum concentration of the peaks varies throughout the column exit section, partially due to the radial variations of the column efficiency. The technology used in constructing the microelectrochemical detectors was further exploited to fabricate and incorporate an online detector array for a pressurized flat wide column measuring 10x10x0.1 cm in dimensions. Thus, unlike traditional thin layer chromatography, samples in this pressurized flat bed are completely eluted and detected in a time-based mode just like they are in HPLC. Also, a lateral arrangement of the detector array allows for an easy monitoring of the homogeneity of the flat wide column. Also, information on the surface properties of three novel chemically bonded phase packing materials for HPLC was obtained using solid state cross-polarization (CP) magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopic experiments for the 29Si, and 13C nuclei. These packing materials were: Cogent bidentate C18 bonded to type-C silica, hybrid packing materials XTerra MS C18, and XBridge Prep. C18. The spectra obtained using cross-polarization magic angle spinning (CP-MAS) on the Cogent bidentate C18 bonded to type-C silica show the surface to be densely populated with hydride groups (Si-H), with a relative surface coverage exceeding 80%. The hybrid packing materials XTerra and XBridge gave spectra that reveal the silicon atoms to be bonded to alkyl moieties embedded in the molecular structure of these materials with over 90% of the alkyl silicon atoms found within the completely condensed silicon environments.

Thesis (Ph. D.)--Indiana University, School of Public and Environmental Affairs, 2006. / Source: Dissertation Abstracts International, Volume: 67-01, Section: B, page: 0156. Adviser: Ronald A. Hites. "Title from dissertation home page (viewed Feb. 22, 2007)."

This Thesis describes applications of standing-waveultrasonic traps for sensitive biomedical analysis. Two majorapproaches have been investigated where functionalizedmicroparticles are employed in bioaffinity assays. In the firstapproach, a longitudinal flow-through capillary ultrasonic trapis used for size selective separation and retention ofdifferently sized microparticles. This device may be used fordetection of particle pairs, which are formed during theinitial stage of microparticle immunoagglutination. Theperformance of the capillary ultrasonic trap for enrichment andcounting of particle pairs is characterized by a model systemof differently sized homogeneous fluorescent microparticles.The selectivity of this detection method relies on thecharacteristics of the force field inside the narrow borecapillary, which is formed by the competition between acousticradiation forces and viscous drag forces from the fluidflow. The second approach is an investigation of the potential forsensitive protein quantification by combining ultrasonicenrichment and confocal laser-scanning fluore-scence detection.Here, the design of the ultrasonic trap is tailor-made for theimaging properties of a confocal microscope, resulting inrearrangement and concentration of suspended microparticlesinto single, dense layers that is scanned by a focused laserbeam. The bioaffinity assay employed is based on detecting thetarget molecules via fluorescent tracer antibodies immobilizedon the surface of each single particle. The final part of the work presented in this Thesis is athorough investigation of both the biochemical and the physicalproperties that determine the performance and potentialsensitivity of the particle doublet assay. In thisinvestigation, a novel approach is presented for doubletdetection, namely fluorescence-microscopy-based classificationof doublets and singlets by a pattern recognition algorithm.The experimental results are also compared with the resultsfrom flow cytometry analysis. Furthermore, the initial stage ofimmuno-agglutination is theoretically investigated by a modelbased on diffusion-limited agglutination combined with a stericfactor determined by the geometry of the bio-molecules and theamount of specific and non-specific binding that is present inthe particular assay. To conclude, the Thesis presents several approaches wherestanding-wave ultrasonic fields may be used for sensitiveparticle-based biomedical analysis. The best prospect for highsensitivity was found for the confocal laser-scanningfluorescence detection system, with a detection limit of theorder of 10-14M. On the other hand, the agglutination-basedassay may give sensitivity of the order of 10-11-10-10M with very simple and inexpensiveequipment.

The novel application of combination, or two stage, photochemical and microbial degradation systems for removal of resin acids from natural river water and single stage photolysis for degradation of naphthenic acids in natural river water was investigated. The organic compounds included in this project comprise naphthenic acid model compounds and mixtures as well as four resin acids. Naphthenic acids are crude oil-derived and accumulate to significant concentrations (>100 mg/L) in tailings pond water at oil sands extraction facilities. Resin acids are pulp and paper mill-derived compounds that tend to persist at low levels in receiving waters. For each compound group, analytical methods utilizing liquid chromatography negative ion electrospray ionization mass spectrometry (LC/ESI/MS) were developed. The main hurdle to developing analytical methods for the naphthenic acids and resin acids are related to their polarity, complexity, and lack of available standards for the various individual components. As well, co-extractives, such as humic and fulvic acids, tend to interfere with the detection of naphthenic acids in aquatic samples (Headley et al., 2002a). Resin acid mixtures are not as complex as the naphthenic acids, although each group of hydrocarbon acids may include several isomeric compounds. The application of photochemical degradation prior to biodegradation was proven to be effective here for rapid degradation of the resin acids. In general, the resin acid precursors were more susceptible to the photolysis than were the naphthenic acids. Through thermal maturation and increased complexity, the naphthenic acids seemingly become more resistant to degradation, as evidenced by their commercial use as anti-microbial agents and the observed resistance to photolysis noted in this research. The results of this research may be significant for the design of staged treatment for reduced microbial shock loading and increased bioavailability (defined here as the ability of microbial organisms to degrade the target contaminants) in both bioremediation systems and receiving waters. Specifically, four selected pulp and paper mill-associated resin acids were exposed to several ultraviolet/visible (UV/vis) spectrum radiation sources in water collected from the River Saale in Germany. Background resin acid concentrations were observed in water collected in 2001 and 2002 from various locations along the well-forested River Saale and a manuscript detailing these results published. Analyses of water samples collected in the pulp and paper milling region of the river (in the state of Thuringia) indicated that resin acids persist through biodegradation treatment systems and for several hundred kilometres downstream. All four resin acids were degraded by facile photochemical and microbial degradation with pseudo-first-order kinetics. Half-life values were in the ranges of 18 to 200 minutes for photolysis applications, 8 to 40 hours for biodegradation applications and 3 to 25 hours for two-stage photochemical-microbial degradation processes, in which photolysis was limited to three hours. From these results, it was shown conclusively that photolysis pre-treatment is a viable and efficient method for reducing both resin acid concentrations and the associated acute toxicity. The naphthenic acids investigated in this study were not effectively degraded via UV/vis radiation, including UV-A/UV-B radiation between 300-400 nm, near-monochromatic UV254-radiation, full spectrum artificial solar radiation and natural sunlight. The photochemical degradation potential of three model naphthenic acid compounds and three naphthenic acid mixtures (one extract from the Athabasca Oil Sands and two commercial mixtures) were examined in Athabasca River water. Photolysis at UV254 was the most successful degradation source in all instances, although most naphthenic acids were not significantly degraded by any of the radiation sources. Therefore, it was determined that photolysis is not likely to contribute significantly to environmental degradation and attenuation in the aquatic ecosystem. The results observed from the various naphthenic acids photodegradation processes, coupled with their low affinity for adsorption to soils, reveal that naphthenic acids are likely to persist in the water column. However, UV/vis radiation is capable of significantly changing the composition of mixtures in the aquatic ecosystem, but not reducing overall naphthenic acid concentrations. This may not be a beneficial as there is the potential for increased toxicity toward the lower molecular weight naphthenic acids.

The novel application of combination, or two stage, photochemical and microbial degradation systems for removal of resin acids from natural river water and single stage photolysis for degradation of naphthenic acids in natural river water was investigated. The organic compounds included in this project comprise naphthenic acid model compounds and mixtures as well as four resin acids. Naphthenic acids are crude oil-derived and accumulate to significant concentrations (>100 mg/L) in tailings pond water at oil sands extraction facilities. Resin acids are pulp and paper mill-derived compounds that tend to persist at low levels in receiving waters. For each compound group, analytical methods utilizing liquid chromatography negative ion electrospray ionization mass spectrometry (LC/ESI/MS) were developed. The main hurdle to developing analytical methods for the naphthenic acids and resin acids are related to their polarity, complexity, and lack of available standards for the various individual components. As well, co-extractives, such as humic and fulvic acids, tend to interfere with the detection of naphthenic acids in aquatic samples (Headley et al., 2002a). Resin acid mixtures are not as complex as the naphthenic acids, although each group of hydrocarbon acids may include several isomeric compounds. The application of photochemical degradation prior to biodegradation was proven to be effective here for rapid degradation of the resin acids. In general, the resin acid precursors were more susceptible to the photolysis than were the naphthenic acids. Through thermal maturation and increased complexity, the naphthenic acids seemingly become more resistant to degradation, as evidenced by their commercial use as anti-microbial agents and the observed resistance to photolysis noted in this research. The results of this research may be significant for the design of staged treatment for reduced microbial shock loading and increased bioavailability (defined here as the ability of microbial organisms to degrade the target contaminants) in both bioremediation systems and receiving waters. Specifically, four selected pulp and paper mill-associated resin acids were exposed to several ultraviolet/visible (UV/vis) spectrum radiation sources in water collected from the River Saale in Germany. Background resin acid concentrations were observed in water collected in 2001 and 2002 from various locations along the well-forested River Saale and a manuscript detailing these results published. Analyses of water samples collected in the pulp and paper milling region of the river (in the state of Thuringia) indicated that resin acids persist through biodegradation treatment systems and for several hundred kilometres downstream. All four resin acids were degraded by facile photochemical and microbial degradation with pseudo-first-order kinetics. Half-life values were in the ranges of 18 to 200 minutes for photolysis applications, 8 to 40 hours for biodegradation applications and 3 to 25 hours for two-stage photochemical-microbial degradation processes, in which photolysis was limited to three hours. From these results, it was shown conclusively that photolysis pre-treatment is a viable and efficient method for reducing both resin acid concentrations and the associated acute toxicity. The naphthenic acids investigated in this study were not effectively degraded via UV/vis radiation, including UV-A/UV-B radiation between 300-400 nm, near-monochromatic UV254-radiation, full spectrum artificial solar radiation and natural sunlight. The photochemical degradation potential of three model naphthenic acid compounds and three naphthenic acid mixtures (one extract from the Athabasca Oil Sands and two commercial mixtures) were examined in Athabasca River water. Photolysis at UV254 was the most successful degradation source in all instances, although most naphthenic acids were not significantly degraded by any of the radiation sources. Therefore, it was determined that photolysis is not likely to contribute significantly to environmental degradation and attenuation in the aquatic ecosystem. The results observed from the various naphthenic acids photodegradation processes, coupled with their low affinity for adsorption to soils, reveal that naphthenic acids are likely to persist in the water column. However, UV/vis radiation is capable of significantly changing the composition of mixtures in the aquatic ecosystem, but not reducing overall naphthenic acid concentrations. This may not be a beneficial as there is the potential for increased toxicity toward the lower molecular weight naphthenic acids.

The energy requirements of forage harvesters can be quite high and can sometimes determine the size of tractor needed on a farm. Therefore, improving the energy efficiency of the forage harvester could allow a farm to reduce costs by using a smaller tractor that is less expensive and more efficient. The objective of this research was to increase the throwing distance of a forage harvester by modeling the flow of forage in the spout and the air flow in the blower and spout. These models can then be used to compare the efficiencies of prototype designs. The air flow in the blower and spout was modeled using the commercial computational fluid dynamics software FLUENT. The simulation results of air velocities and flow patterns were compared to experimental values and it was found that both were of the same order of magnitude with the model predicting slightly higher air velocities than those measured. The flow of forage in the spout was modeled analytically by taking into account the friction between the forage and the spout surface and the aerodynamic resistance after the forage leaves the spout. From this model, two improved prototype spouts that should theoretically result in longer throwing distances were designed. However, field testing of the two prototypes did not reveal any significant improvements over the current design. It was also found that the model under-predicted the throwing distance of one prototype by 2 % and over estimated the other by 12 %.

This research intends to introduce a model in order to choose the best Maintenance Strategy based on the condition of the relevant company. Basically, it is divided into three main parts. First part is the theoretical part and deals with the Maintenance approaches, conceptions, cost, software, and management. Second part explains the structure of selecting maintenance strategy by using improved Analytical Hierarchical Process (AHP) method and describes some definitions and equations in this scientific method. In the third part, a hypothetical example shows the accuracy of the method and the way it works.

This thesis describes a series of experiments designed to examine the use of Au nanoshells as highly controllable surface enhanced Raman spectroscopy (SERS) nanosensor substrates. Individual Au nanoshells provide simple, scalable substrates for SERS with demonstrated strong electromagnetic field enhancements which exist near the molecule-substrate interface. The SERS spectral response is explored as a function of analyte concentration, environmental pH, and various analyte properties and composition. As a function of analyte concentration, the SERS response is exploited for the determination of packing density and molecular conformation of thiolated poly(ethylene glycol) (PEG) adsorbates on Au nanoshells. By varying the environmental pH when a pH-sensitive molecular adsorbate is attached to the Au nanoshells, the resultant SERS spectra allow for local pH monitoring with an average accuracy of +/-0.10 pH units across the operating range of the nanodevice. Changing analyte properties, such as carbon chain length for alkanethiol self-assembled monolayers (SAMs) on gold, produces a series of sharp resonances in the SERS spectra, suggesting coupling of the gold-sulfur bond stretch with the longitudinal acoustic, "accordion", vibrations of the molecular alkane chain. Further variation in chain termination or the addition of a phospholipid headgroup yields observable SERS spectral differences, providing unique fingerprints for each molecule. An associated phospholipid layer assembled onto an underlying alkanethiol SAM forms a hybrid bilayer on Au nanoshells, providing a way to spectrally monitor intercalation of the nonsteroidal anti-inflammatory drug (NSAID), ibuprofen. Low frequency SERS peaks for halogen, nitrogen, and oxygen containing molecules act as probes for metal-adsorbate binding, with spectral evidence for carbon monoxide adsorption occurring in the high frequency region. Finally, we demonstrate the synthesis and characterization of nanoparticles composed of magnetic cores with continuous Au shell layers that simultaneously possess both magnetic and plasmonic properties. The work presented in this thesis further demonstrates the emergence of Au nanoshells as versatile and valuable tools for sensing applications.

Ambient particulate matter samples were collected at various sites in Texas, Arizona, and Austria from 2005 to 2009 to characterize the organic compositions and local PM sources. The primary biologically derived carbon sources, specifically the atmospheric entrainment of soil and associated biota and primary biological aerosol particles (PBAPs), are major sources contributing to ambient PM. This dissertation work proposes simple saccharides as well-suited tracers to characterize the contribution to ambient PM from these primary biologically derived carbon sources. Saccharide concentrations in ambient PM were determined from various locations and various seasons. Aerosol saccharide compounds displayed seasonal variations, inter-correlations, and size fractionations (fine vs. coarse) that were consistent between samples and that can be used to determine sources. The difference in aerosol saccharide concentrations and relative species abundances was reflective of different climate patterns and ecosystems. Selected saccharide compounds including an established marker (levoglucosan) and novel markers (glucose, sucrose, trehalose, mannitol, and arabitol) were used along with other markers to model the major source contributions to ambient PM using a positive matrix factorization (PMF) model. Major local PM sources were resolved at three Texas sites (San Augustine, Dallas, and Big Bend National Park) and one Arizona site (Higley), with two source factors enriched in the proposed novel saccharide markers that can be related to the primary biologically derived carbon sources. The contribution to PM from the saccharide-rich primary biological sources was estimated to range from 16% (remote area) to 36% (rural and suburban area) at the four sampling sites studied. Other PM sources identified by PMF included motor vehicles, secondary aerosol formation, meat cooking, biogenic wax, sea salt, crustal material, and road dust. To further characterize the primary biologically derived carbon sources, different soil and source samples representing PBAPs (plants and spores) were collected at Higley (AZ) to study their saccharide compositions in particle sizes equivalent to PM2.5 and PM10. It was found that the total measured non-levoglucosan saccharide content relative to PM mass in ambient aerosols (0.2% on average in PM2.5 and 0.11% in PM10) was much higher than the soil samples (<0.02% in both PM2.5 and PM10) but much lower than in the PBAP source samples (2% on average in plant PBAP samples and 16% in spore PBAP samples). The measured PBAP samples contained a concentration of sucrose and glucose that is consistent with the saccharide-rich source profiles resolved from ambient aerosol data analyzed by PMF while the measured soil samples did not. This can be interpreted as confirmation that PBAPs are an important PM source in additional to soil and associate biota at Higley, AZ. However, the saccharide levels in the measured PBAP samples were several orders of magnitude higher than the PMF results, suggesting that the ambient aerosol samples are a combination of high saccharide concentration PBAPs and lower saccharide concentration soils at Higley, AZ.

The energy requirements of forage harvesters can be quite high and can sometimes determine the size of tractor needed on a farm. Therefore, improving the energy efficiency of the forage harvester could allow a farm to reduce costs by using a smaller tractor that is less expensive and more efficient. The objective of this research was to increase the throwing distance of a forage harvester by modeling the flow of forage in the spout and the air flow in the blower and spout. These models can then be used to compare the efficiencies of prototype designs. The air flow in the blower and spout was modeled using the commercial computational fluid dynamics software FLUENT. The simulation results of air velocities and flow patterns were compared to experimental values and it was found that both were of the same order of magnitude with the model predicting slightly higher air velocities than those measured. The flow of forage in the spout was modeled analytically by taking into account the friction between the forage and the spout surface and the aerodynamic resistance after the forage leaves the spout. From this model, two improved prototype spouts that should theoretically result in longer throwing distances were designed. However, field testing of the two prototypes did not reveal any significant improvements over the current design. It was also found that the model under-predicted the throwing distance of one prototype by 2 % and over estimated the other by 12 %.