This thesis details research undertaken in the investigation of the open-shell open-shell Van der Waals complexes between nitric oxide (NO) and oxygen (O₂) and between nitrogen dioxide (NO₂ ) and oxygen (O</sub>2</sub> ). The Fourier transform microwave spectroscopy technique was used during the experimental work. Spectra were recorded for a mixture of NO and O₂ over the frequency range 7.0 to 18.2 GHz. Detailed ab initio calculations have been performed on the potential energy surface of both NO-O₂ and NO₂-O₂ using Multi-reference Rayleigh Schrodinger Second Order Perturbation Theory. These calculations were performed for the four distinct states of NO-O₂, ²A", ⁴A", ²A' and ⁴A', and for the two distinct states of NO,sub>2</sub>-O₂, ²A and ⁴A. Predicted rotational spectra have been generated by modelling the systems with a rigid-rotor Hamiltonians. The effective Hamiltonians included the rotational Hamiltonian, ℋ_rot, fine structure terms and hyperfine structure terms. It was not possible, for rationalizable reasons, to fit the predicted spectra for NO-O₂ to the experimental observations. Experimental details, calculation methods and rotational theory are discussed in the main body of the thesis. Predicted spectra, relevant calculations and other data is presented in the appendices.

The potential applicability of Fourier transform infrared (FM) spectroscopy for the study of biomolecules, has been investigated through the investigation of three specific applications. Two of the applications selected involve the classification of whole cells, whereas the third concerns the study of peptides and proteins isolated from tissues as well as synthetic peptides. In the microbiological application, for the differentiation of bacteria on the basis of their FTIR spectra, it has been found that classification is most efficiently achieved through the utilisation of artificial neural networks, and that a wide, variety of bacteria can be correctly identified with minimal sample preparation after being grown on a single growth medium. The suitability of low-cost, disposable materials as supports for the deposition of bacteria samples has also been demonstrated. In contrast to the successful classification of bacteria, it has been found that the examination of cytological smears by FTIR spectroscopy does not allow the classification of cervical cell populations into the recognised diagnostic categories. In a microscopic investigation of the same cell populations utilising infrared imaging, localised areas of the smear were found to exhibit distinct characteristics not observed in the spectra of the entire population. This indicates that infrared imaging system may be required for this type of application because the infrared spectrum recorded from a whole cervical smear does not allow the detection of the small spectral features arising from the molecular changes associated with a localised pathological state. Finally, the investigation of factors affecting the stability of peptides related to amyloidosis has shown that temperatures above 70°C, hydrostatic pressure greater than 6 kbar, and alkaline pH promote the disaggregation of the typical intermolecular beta-sheet structure of amyloid peptides. Peptides utilised as model systems for amyloidosis showed

This thesis presents the design, fabrication, and testing of a micromixing device intended for use in investigating protein dynamics on a microsecond timescale by Fourier transform infrared (FTIR) spectroscopy. Numerical modeling of flow was implemented to predict the influence of flow rates and geometric variations on mixing performance in three passive mixers. The simulation models were validated by experimental measurements using optical and infrared detection. The optimum level of mixing was observed in a multi-lamination mixer that combined thin filaments of differing fluids in an alternating manner. The multi-laminates were transferred onto polished calcium fluoride infrared-transparent optical windows by lithographic processing of an Epon-based polymer, SU-8. A rigid seal between two microchannels was accomplished through thermal bonding of an unexposed resist layer, which acted as a thermal epoxy under the influence of temperature. The multi-lamination mixer was used to study the changes in the secondary structure of beta-Lactoglobulin in deuterated phosphate buffer under varying physicochemical conditions by time-resolved FTIR spectroscopy using focal plane array detection. Upon a pH jump from pH 2 to neutral pH, a gradual loss of alpha-helical content, accompanied by an increase in random coils and turns was observed within 2 ms of mixing. In a second kinetic experiment, mixing of a neutral-pH solution of beta-Lactoglobulin with a 60% trifluoroethanol solution resulted in the formation of an alpha-helical intermediate with an accompanying increase in intramolecular beta-sheet structure within 500 mus of mixing. These results indicate that the multi-lamination mixer designed and fabricated in this study is well suited for investigations of protein dynamics on the micro- to millisecond timescale by time-resolved FTIR spectroscopy.

The utility of focal-plane-array Fourier transform infrared (FPA-FTIR) spectroscopy as a rapid method for the differentiation of antibiotic resistant foodborne pathogens was studied. / Optimum spectral acquisition and processing parameters as well as appropriate film thickness of bacterial films were empirically established for the discrimination between two Shigella species (S. flexneri and S sonnei) in order to optimize the scanning parameters of an FPA-FTIR spectrometer. A detailed study of the potential of FPA-FTIR spectroscopy for the discrimination between antibiotic resistant and sensitive strains from two Salmonella species (S. Typhimurium and S. Heidelberg) was subsequently undertaken. The results of these studies demonstrated that the infrared spectra recorded by an FPA-FTIR spectrometer contained sufficient information to differentiate between antibiotic resistant and sensitive strains of Salmonella. Accordingly, FPA-FTIR spectroscopy may potentially serve as a high-throughput technique for the identification of foodborne as well as antibiotic resistant bacteria. / Interpretation of the regions selected in relation to the different resistance mechanisms would require more detailed studies. However, the identification of specific biochemical markers based on such spectral interpretation is generally not feasible owing to the complexity of the FTIR spectra of microorganisms.

New Fourier transform infrared (FTIR) approaches for the quantitative determination of peroxide value (PV) and isolated trans analyses were investigated and developed. The FTIR-PV methods investigated were all based on the stoichiometric reaction of hydroperoxides and triphenylphosphine (TPP) which converts TPP to triphenylphosphine oxide (TPPO). A reference transmission cell (100 mum) method was developed based on the use of a unique TPPO absorption at 542 cm-1. This method covered PV values from 0--15 PV and was shown to be superior in accuracy and reproducibility to the standard American Oil Chemists Society (AOCS) iodometric method. Subsequently, the utility of disposable polyethylene cards, normally used only for qualitative analyses, was investigated for quantitative PV determination. A quantitative IR card method was successfully developed and shown to serve as a very simple, rapid and alternative means of carrying out PV analyses. TPP-impregnated cards were able to reproduce the transmission cell PV results to +/-1.12 PV, while the unimpregnated card was slightly more accurate (+/-0.92 PV). A third FTIR-PV method was developed specifically for the at-line monitoring of high PV fatliquors and employed a germanium attenuated total reflectance sample handling accessory. This method hinged on the use of a TPPO absorption band at 1118 cm-1, normally off scale when pathlengths of >3 mum are used, but is suited to the analysis of oils having very high PVs (>250). The successful quantitative use of the disposable polyethylene IR card to PV led to its study for the quantitative FTIR determination of the isolated trans content of fats and oils and margarines. The polyethylene card was shown to unique and useful properties, tending to inhibit fat crystallization and its inability to retain moisture. These two properties allowed trans determination to be carried out on melted, high trans fats, without heating the polyethylene substrate and also to analyze margarines

The infrared spectra of 14 bacteria were recorded by Fourier Transform Infrared (FTIR) spectroscopy. The effects of changes in growth conditions, such as temperature, growth medium, and incubation time, sampling conditions on the reproducibility of the spectra were investigated. The spectra of bacteria suspended in saline solution, in D$ sb2$O-saline and on plate films were obtained and stored in separate spectral libraries. The application of library search routines for differentiation and identification of the 14 bacteria was investigated. The spectral regions used for the library search include 1750-1560 cm$ sp{-1}$ and 1480-960 cm$ sp{-1}$, which contain bands mainly associated with proteins (secondary structure), lipids, and polysaccharides. An index produced by the library search, which indicates how much an "unknown spectrum" matches a library spectrum, is suggested as a criterion for the differentiation and identification of bacteria. A correct identification of five unknown samples shows the feasibility of using spectral library searching routines for identification of bacteria down to the species level by FTIR spectroscopy. This technique is rapid, easier, and more efficient than conventional microbiological and biochemical methods. Quantitative analysis of a mixture of Escherichia coli and Staphylococcus aureus by the partial-lest-square (PLS) technique was also evaluated. The analytical error was about 10%.

The utility of single-bounce attenuated total reflectance (SB-ATR) and heterospectral two-dimensional correlation spectroscopy (H2D-CS) in quantitative analysis by Fourier transform infrared (FTIR) spectroscopy was investigated by exploring several potential applications of these techniques. Enzymatic hydrolysis of lactose in milk was monitored by SB-ATR/FTIR spectroscopy, and changes in the concentrations of glucose, galactose and lactose during the process were successfully measured quantitatively. SB-ATR/FTIR spectroscopy was shown also to perform comparably to Fourier transform near-infrared (FT-NIR) spectroscopy for the determination of the alcohol content of distilled liquors and better than FT-NIR spectroscopy and comparably to transmission FTIR spectroscopy for the analysis of alcohol, total reducing sugar, total acidity and pH in wines. In addition, a set of 149 pre-analyzed wine samples was employed to develop and validate an SB-ATR/FTIR calibration for 11 different parameters and constituents in wines with the use of partial-least-squares (PLS) regression, demonstrating the potential utility of this method in the routine analysis of wines. The application of SB-ATR/FTIR spectroscopy and H2D-CS in the selection of wavelengths for multiple linear regression (MLR) calibration for FT-NIR analysis of ternary aqueous solutions of fructose, glucose and galactose was also investigated. NIR wavelengths were identified for the three sugars by H2D-CS of the SB-ATR/FTIR spectra of binary sugar solutions in relation to their FT-NIR spectra. An MLR calibration developed based on these wavelengths gave better results than PLS calibrations and comparable results to those obtained by MLR using wavelengths selected by examination of 1st and 2nd derivative spectra. H2D-CS was extended to include 2D correlations between high-pressure liquid chromatography (HPLC) and SB-ATR/FTIR data for the purpose of identifying HPLC peaks without the need to isolate the eluted compounds. The potential utility of this approach, termed spectroscopic/chromatographic 2D correlation (SC2D-C), was investigated by generating FTIR slice spectra corresponding to the HPLC peaks of wines spiked with sucrose, glucose and fructose and comparing them to 404 reference spectra in an IR spectral library. It was found that these constituents were correctly identified provided there was sufficient random variability of their concentrations in the samples analyzed.

No description available.

Environmental and food spoilage fungi cause billions of dollars in damage in North America alone each year, in the form of rotted wood and crops, spoiled food, and human and animal illness. Each of these threats could be drastically reduced if early and more rapid detection processes are developed to replace the serological methods that are currently in practice. The current North American protocol for establishing identification of contaminating fungi both in environment and food have a time frame of approximately one week to twenty-two days. The use of a Fourier transform infrared (FTIR) spectrometer, coupled with a focal-plan-array (FPA) detector, can theoretically shorten the time (analysis within minutes after obtaining a pure culture) it takes to identify and classify a fungal cell. FPA-FTIR spectroscopy is advantageous as little to no sample preparation is required and results are obtained in less than one minute per sample. The fungal subset chosen for this study includes representatives from five phyla, including Zygomycota (Mucor heimalis), Ascomycota (Neurospora crassa, Ophiostoma minor, Chaetomium globosporum, Alternaria brassicicola), Basidiomycota (Schizophyllum commune, Chaetomium globosporum), Deutromycota (Aspergillus niger, Penicillium notatum, Aureobasidium pullulans) and the Mycetozoa (dictyostelium discoideum, physarum polycephalum). Different variables were tested and evaluated, including variability in growth parameters, wet deposition of fungi versus dry smearing of fungi, optimal absorbance range, and spectral processing parameters as well as discrepancies from one instrument to another, as well as spectral reproducibility from one instrument to another. By following the experimental protocol developed, reproducible spectra were attained, and differentiation of the fungi within the set selected for this study was achieved. The results of this work demonstrate that FPA-FTIR spectroscopy can potentially be employed for the accurate identification of environmental and food spoilage fungi.

Hyperbaric pressure has been shown to affect the secondary structure of whey proteins such as beta-lactoglobulin (beta-lg). There is limited research, however, regarding the optimal conditions by which pressurization of whey proteins could lead to irreversible changes in secondary structure including the reduction of intramolecular disulfide bonds. Irreversible changes in protein conformation and breakage of disulfide bonds of whey proteins induced by high pressure might result in an increase in their digestibility and a reduction of allergenicity. Hence, the overall objective was to explore the capability of hyperbaric pressure to alter irreversibly the secondary structure of whey proteins and thereby alter their allergenic and nutritional properties. The behaviour of different genetic variants of beta-lg was studied employing variable-pressure Fourier transform infrared (FTIR) spectroscopy to establish the optimum pressures needed for their denaturation. The results showed reversible effects of pressures up to 12.0 kbar on the secondary structure of three main genetic variants of beta-lg. The individual response of the genetic variants to pressure was distinguishable despite their subtle structural differences. Pressure-induced conformational changes were studied separately in bovine serum albumin, Ca++-saturated alpha-lactalbumin and Ca ++-free alpha-lactalbumin by FTIR spectroscopy. The studies revealed that the presence of Ca++ ion and the number of disulfide bonds protects the protein molecules against pressure. As whey proteins appeared to be resistant to denaturation upon single applications of high pressure up to 1200 MPa, we developed a novel pressure processing using a combination of pulse and continuous modes at lower pressures of 400 MPa which led to irreversible denaturation of whey protein structure and disulphide bond breakage. Weanling rats fed with whey protein isolates treated by this novel low pressure processing technique showed enhanced grow