Chlorpheniramine, a reversible competitive inhibitor at the H1-receptor that has demonstrated potent, long-lasting antihistaminic activity with only mild side-effects, has been a popular choice for the treatment of allergic conditions and is a common component of cold/cough preparations. A number of groups have studied the pharmacokinetics of chlorpheniramine since its development, but results have been conflicting. Moreover, most of the pharmacokinetic studies had only involved analysis of the parent compound and excluded pharmacologically active metabolites. / As part of a new pharmacokinetic study of chlorpheniramine, an enantiomeric method to resolve chlorpheniramine from its N-demethylated metabolites and chlorpheniramine N-oxide was required. The use of high performance liquid chromatography (HPLC) with the amylose tris(3,5-dimethylphenylcarbamate) chiral stationary phase (AD-CSP) failed to resolve the enantiomers of chlorpheniramine and its metabolites. Capillary electrophoresis was used to screen a number of chiral selectors including hydroxypropyl beta-cyclodextrin, sulfated beta-cyclodextrin and carboxymethyl beta-cyclodextrin. The resolution of the enantiomers of chlorpheniramine and its metabolites was achieved using carboxymethyl beta-cyclodextrin obtained from Wacker Chemie, Munich, Germany. Detection limits of chlorpheniramine down to 200 ng/mL were achieved by concentrating samples and using sample stacking methods.

The changes which occur in water absorbance in the near-infrared (NIR) region, specifically at 960 nm, are correlated to tissue temperature. One of the temperature-varying constituents of tissue is the change which occurs in the hydrogen-bound states of water. As the temperature is raised, there is an exchange of water species from the hydrogen-bound to non-hydrogen bonding. The aim of this thesis is to determine tissue temperature from NIR spectral profiles of tissue as temperature is increased. A NIR probe was used to obtain spectral profiles for a series of tissue measurements. / Using the data sets obtained, in-vitro measurements conducted on bovine lung tissues show that temperature can be measured to 1.0°C. Likewise, in-vivo measurements conducted on the human finger also show that temperature can be measured to 2.1°C precision. These measurements suggest that tissue temperature can be measured in living systems using NIR temperature detection.

The overall objective of this study was to develop a fluorescent chemosensor for cAMP by creating recognition sites for cAMP, that contain a fluorescent molecule, in a polymer matrix by molecular imprinting. Such a fluorescent molecularly imprinted polymer may, therefore, serve as both the recognition element and the measuring element for the fluorescent detection of cAMP in aqueous media. / Two new fluorescent molecules, known as 4-(p-dimethylaminostyryl)pyridinium salts or dyes, were synthesized as possible fluorescent components of a chemosensor. Upon excitation at 469 run, dye 1, trans-4-( p-N,N-dimethylaminostyryl)-N-vinylbenzyl-pyridinium chloride, displays a dramatic quantum yield enhancement in an emission band centered at ∼600 nm, with concomitant slight red shift of the emission maximum, in the presence of the cyclic nucleotides, cAMP and cGMP, in aqueous solution. Other purine nucleotides (AMP, ADP and ATP) and adenosine induce fluorescence quantum yield enhancements of lesser magnitude than those observed for cyclic nucleotides. The pyrimidine nucleotides, CMP and UMP, have almost no effect on the fluorescence of 1, suggesting a specificity of 1 for purine over pyrimidine analytes. Equilibrium association constants for 1 with the purine analytes, in aqueous solution (pH 7.2) range from 13.9 M --1 for cAMP to 0.15 M--1 for adenine. We conclude that the interaction of 1 with these analytes requires the presence of a purine base, and is enhanced by the presence of ribose and phosphate moieties. Dye 1 and a structurally-similar dye 2, trans-4-(p-N,N-dimethylaminostryl)-N-phenethylpyridinium bromide, also display dramatic fluorescence enhancements in the presence of DNA and proteins, suggesting that they also interact with these biomolecules. The environmentally-sensitive fluorescence of dyes 1 and 2 suggests that such compounds may be useful for developing fluorescent chemosensors for purine nucleotides, especially cAMP, and for the fluorescence detection or staining of DNA and proteins. / To increase the recognition ability of 1 for cAMP, we prepared recognition sites for cAMP that contain fluorescent dye 1 in a polymer matrix by molecular imprinting. This is a novel design for such template-selective sites, since dye 1 forms an integral part of the recognition cavity, thereby serving as both the recognition element and the measuring element for the fluorescence detection of cAMP in aqueous media. The polymer displays a concentration-dependent decrease in fluorescence in the presence of aqueous cAMP, whereas almost no effect is observed in the presence of the structurally-similar molecule, cGMP. An association constant of ∼105 M--1 was calculated for cAMP binding. Such fluorescent molecularly imprinted polymers could serve as a starting point in the development of highly effective synthetic fluorescent sensors for cAMP as well as other important biological molecules.

The principal objectives of this thesis are to introduce a new method, colloidal particle scattering (CPS), to measure colloidal and surface forces, and to demonstrate various applications of this method. CPS determines particle-particle interaction forces through creating particle collisions and extracting the interaction forces from the degree of asymmetry of the collision trajectories. Since the force to deflect a micron-sized particle is much smaller than that to deform a macroscopic spring or cantilever used in a commercial force apparatus, this new technique increases the resolution of force determination by four orders of magnitude. / Based on the CPS principles, we have built a force apparatus called "microcollider". It successfully determined the van der Waals forces and the electrostatic force between two 5 $ mu$m latex spheres at different salt concentrations. A "hairy" latex model was introduced to explain the measured van der Waals forces which are weaker than those predicted by theory assuming smooth latex surfaces. This is consistent with other experimental findings about the surfaces of latex particles. / A similar "hairy" model was applied to determine the adsorption layer thicknesses of two triblock copolymers adsorbed on latex particles. The results show that the configuration of the buoy block composed of polyethylene oxide (PEO) is more extended than a random PEO coil, which agrees with theoretical predictions. Moreover, excellent quantitative agreement between the adsorption layer thicknesses determined by CPS and other methods has been found. / Dynamic steric interactions between two high molecular weight PEO adlayers have also been studied. Both the elastic modulus and the adsorption layer thickness were determined. The results show that a thick layer has a lower elastic modulus than a thin one composed of the same polymer. This implies that an extended loop/tail structure in a thick layer is less stiff than a flat compact one in a thin layer, which is consistent with theory. / In addition, the microcollider can accurately determine particle-wall interactions as well. A rather weak electrokinetic lift force was measured. The results are in good agreement with the solutions rigorously derived from two new theories.

The purpose of this study is to find analytical solutions to Laplacian field problems rela-tive to arbitrary configurations of spheres based on novel translational addition theorems derived specifically for scalar Laplacian functions. These theorems are used to express in analytic form the fields due to individual spheres in system of coordinates attached to other spheres, thus allowing for the exact boundary conditions to be imposed. In the literature, translational addition theorems are available for scalar cylindrical and spherical wave functions. Such theorems are not directly available for the general solu-tion of the Laplace equation. This thesis presents the derivation of the required translational addition theorems for the general solution of Laplace equation in spherical coordinates and then the application of these theorems to find analytical solutions to some electrostatic and magnetostatic field problems relative to arbitrarily located spheres. Computation results for electric and magnetic spheres have been generated and numerical results are compared with the re-sults obtained by other methods available in the literature for two sphere systems. Such numerical data, of known accuracy, are also useful for validating various approximate numerical methods.

Residual dipolar couplings have been introduced recently as a new type of experimental constraints in biomolecular structure determination by nuclear magnetic resonance (NMR). These interactions are obtained by imparting weak orientational ordering to a biomolecule in a dilute liquid crystal. This results in a partial cancellation of anisotropic interactions such as the chemical shift anisotropy (CSA), the quadrupolar coupling and the dipolar coupling. Because the alignment is weak, only strong interactions manifest. These measurements can be used to refine structure or to define folds in structural genomics projects. Here, I demonstrate the use of a new alignment medium that consists of a nematic Pf1 bacteriophage suspension embedded in an aqueous polyacrylamide gel matrix. In the absence of the gel, the phage particles align spontaneously in the NMR field.

No description available.

<p>Over half of the biosolids produced in wastewater treatment facilities in the United States are land-applied as a nutrient-rich soil amendment. However, these biosolids are not regulated for chemicals of emerging concern that are often present at high concentrations in biosolids. The overall goal of this dissertation is to evaluate the specific chemical fates of these compounds in biosolid-amended soil, including their persistence, degradation pathways, and phytoaccumulation potential. </p><p>As a first step toward this goal, the fate of select brominated flame retardants (BFRs) when exposed to sunlight was examined to evaluate their photodegradation pathways and to identify degradation products that may be used as markers of environmental degradation in future studies. In Chapter 2, the photodegradation of three polybrominated diphenyl ether (PBDE) congeners (i.e., the nonabrominated congeners BDE 206, 207, and 208) was examined individually in three different solvents exposed to natural sunlight. Rapid degradation of nonaBDEs was observed coincident with formation of octa- and heptabrominated PBDEs. The photodegradation pathways of each nonaBDE congener were consistent among the different solvent matrices tested; however, mass balances were found to vary with solvent type. The octabrominated congener, BDE 202, and the ratio of BDE 197 to BDE 201, were identified as degradation products that can serve as environmental markers of debromination. Additional photodegradation studies were conducted with two new BFRs used in replacements for pentaBDE mixtures: 2-ethylhexyltetrabromobenzoate (TBB) and di(2-ethylhexyl)-tetrabromophthalate (TBPH). Both TBB and TBPH underwent photolysis more slowly than nonaBDEs and primarily formed debrominated products. This study is the first to report on the photodegradation of TBB and TBPH via debromination reactions and suggests that these replacement flame retardants may be more photolytically persistent than higher brominated PBDE congeners.</p><p>Chemical analysis of biosolids collected from wastewater treatment plants (WWTPs) can help determine whether these flame retardants are migrating from the indoor environment to the outdoor environment, where little is known about their ultimate fate and effects. In Chapter 3, concentrations of a suite of flame retardants and the antimicrobial compound triclosan were measured in opportunistic samples of municipal biosolids and the domestic sludge Standard Reference Material (SRM) 2781. Grab samples of biosolids were collected from two WWTPs in North Carolina and two in California. Biosolids samples were also obtained during three subsequent collection events at one of the North Carolina WWTPs to evaluate fluctuations in contaminant levels within a given facility over a period of three years. The biosolids and SRM 2781 were analyzed for PBDEs, a suite of alternate brominated and chlorinated flame retardants, and triclosan. PBDEs were detected in every sample analyzed, and &#931;PBDE concentrations ranged from 1750 to 6358 ng/g dry weight (dw). Additionally, the PBDE replacement chemicals TBB and TBPH were detected at concentrations ranging from 120 to 3749 ng/g dw and from 206 to 1631 ng/g dw, respectively. Triclosan concentrations ranged from 490 to 13,866 ng/g dw. The detection of these contaminants of emerging concern in biosolids suggests that these chemicals have the potential to migrate out of consumer products and enter the outdoor environment. Furthermore, land application of these contaminated biosolids may result in soil contamination and enhance the bioaccumulation and long-range transport potential of these compounds. </p><p>In order to fully evaluate the benefits and impacts of biosolids land application, a comprehensive view of the behaviors of chemicals of emerging concern in biosolids is needed. In Chapter 4, the fates of a suite of flame retardants and triclosan in soil were evaluated in a greenhouse experiment utilizing three biosolid amendment levels (control, low, and high) and two vegetation treatments (unplanted and planted with alfalfa (<italic>Medicago sativa</italic>)). BDE 47, BDE 209, TBB, TBPH, and triclosan declined significantly in the high biosolid-amended vegetated soil between Days 0 and 28 (p < 0.05), and then reached a plateau between Days 28 and 90 during which no further significant loss from soil was observed. In contrast, no significant losses of those analytes were observed from soil at the high biosolids amendment in non-vegetated pots. The percent of a given analyte lost from the vegetated soil at the high amendment between Day 0 and the plateau ranged from 43.1% for TBPH to 60.9% for triclosan and was significantly and negatively related to the log octanol-water partition coefficient (log K_OW) of the analyte (p = 0.0103, R<super>2</super> = 0.9178) and marginally significantly and positively related to the log of water solubility (p = 0.0686, R<super>2</super> = 0.7213). Alfalfa root and shoot tissues were monitored for the analytes of interest but no clear evidence of phytoaccumulation was observed. Methyl triclosan formation was observed in the biosolid-amended soils during the study period, indicating that biotransformation played a role in the observed dissipation of triclosan. The results of Chapter 4 demonstrate that PBDEs, selected alternate BFRs and triclosan are highly recalcitrant in biosolid-amended soils but capable of undergoing dissipation in the presence of alfalfa and, in the case of triclosan, biotransformation. </p><p>In conclusion, this dissertation provides a comprehensive view of the fates of flame retardants and triclosan in biosolid-amended soil, identifying markers of degradation that can be used in complex real-world scenarios, developing methods for measurement of a diverse suite of analytes in biosolids and plant tissues, and demonstrating the persistence of these compounds in biosolid-amended soil.</p> / Dissertation

<p> Several heterogeneous catalysts were studied for synthesis gas production through dry reforming of methane (DRM). This process uses carbon dioxide in lieu of the steam that is traditionally used in conventional methane reforming to produce hydrogen that can then be repurposed in more chemical processes [2]. The monometallic catalysts explored were Ni/Al₂O₃ and Ni/CeZrO₂ followed by their bimetallic versions PtNi/Al₂O₃ and PtNi/CeZrO₂ at 800&deg;C. In addition to these catalysts, platinum supported Zeolitic Imidazolate Framework (ZIF)-8 was also investigated in comparison with PtNi/CeZrO₂ at 490&deg;C. The studies suggest that these catalysts are suitable for promoting the dry reforming of methane for hydrogen production.</p>

No description available.