No description available.

No description available.

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.

Firefighters’ coats and pants, referred to as firefighters’ protective clothing in this research, are made of similar fabrics and often include three layers: an outer shell, a moisture barrier, and a thermal liner. Minimum requirements of firefighters’ protective clothing performance have been clearly established by various national and international standards for new clothing to ensure the reasonable safety of firefighters. However, there are no clear guidelines on the requirements for continuing performance of firefighters’ protective clothing. In general, the protection offered by firefighters’ protective clothing is expected to deteriorate over time, but it is still uncertain how destructive different exposures are and how long a piece of firefighters’ protective clothing can continue to protect a firefighter to an acceptable level. Non-destructive techniques are preferable in order to investigate how the performance of protective clothing may change with time since this allows firefighters’ protective clothing to return to service after a test. These non-destructive methods, which could be used to monitor the level of deterioration in firefighters’ protective clothing performance and to make decisions on retirement of individual pieces of protective clothing, would be extremely useful for fire departments in Canada and other countries. Thermal exposure is an important factor in ageing of firefighters’ protective clothing during firefighting operations. Outer shell and moisture barrier specimens made of common fabrics used in construction of firefighters’ protective clothing, and of different colours, were exposed to different levels of thermal exposure simulated using a cone calorimeter in single and multiple stages. Tensile strength of outer shell specimens, and tear strength, water vapour transmission rate, and water penetration pressure of moisture barrier specimens, which are critical aspects of performance of firefighters’ protective clothing, were measured. In order to explain the changes in performance after thermal exposure, the temperature profile of specimens during each thermal exposure was recorded. Furthermore, thermogravimetric analysis for each specimen material was carried out and images of the surface of specimens were obtained using scanning electron microscope. The test results demonstrated that tensile strength of outer shell specimens deteriorated faster than other aspects of performance. Two non-destructive techniques, colour measurement and near infrared spectroscopy, were implemented to correlate tensile strength of outer shell specimens with discoloration and reflectance spectrum. Two types of correlation between tensile strength and colour change were identified among the tested fabrics, depending on the initial fabric colour, which could be a basis to develop numerical models to predict tensile strength of outer shell specimens. Linear predictive equations were developed using a numerical code based on regression analysis, which correlated tensile strength with reflectance of outer shell specimens within the wavelength region of 1500-2500 nm. A three-variable model predicted tensile strength of thermally aged test specimens, the tensile strength of which were 600 N and higher, with a relative error of up to 10%. For test specimens with tensile strength of about 300 N, the relative error was 55%. The difference in error percentage was related to a gap in training data points for the model within the tensile strength range of 300 - 600 N.

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.

The physical characteristics and reactivity of a number of commercially available samples of calcium oxide and hydroxide were investigated. 'Fresh' and 'aged' (Le. exposed to the atmosphere) samples were characterised by Fourier Transform Infra-Red Spectroscopy, Thermo-Gravimetric Analysis, Nitrogen Adsorption, Water Adsorption, Scanning Electron Microscopy and Microprobe Analysis. From this slight differences in the 'fresh' samples were found to be due to various degrees of atmospheric ageing. The main process involved in the ageing process was confirmed to be carbonatation (or carbonation). This ageing process was then followed by analysing a sample of calcium hydroxide over a long time period (350 days) and by looking at variations in the process by exposure of the sample to various gases and vapours, i.e. water, dried carbon dioxide, deuterium oxide, ethanol and methanol. These experiments showed that the reaction probably proceeded by a direct reaction between the carbon dioxide gas and the solid and confirmed that water was important when considering the rate of the carbonatation reaction. This was thought to be due to its influence in disrupting the calcium hydroxide structure, thus allowing new surface to become available for reaction and allowing the formation of a bulk calcium carbonate structure. Water adsorption isotherms carried out on the calcium hydroxide at elevated temperatures (250°C and above) showed that outgassing at such temperatures caused a partial decomposition to calcium oxide but that the original calcium hydroxide structure remained intact. These isotherms also had negative hysteresis which was thought to be due to the take up of water in an expanded skeletal calcium hydroxide structure which was expelled from the structure when it fully reconstituted at higher relative pressures to reform calcium hydroxide.