Thesis (M. Sc.)--University of Hong Kong, 1973. / Typewritten.

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No description available.

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Functional near-infrared spectroscopy (fNIRS) is a non-invasive technique for monitoring of brain functional activity. It uses near-infrared (NIR) light to get the information related to brain hemodynamic response as most of the tissues in the brain are transparent to NIR light. The main goal of this study was to design, implement and evaluate a continuous-wave near-infrared spectroscopy (CW-NIRS) system for human’s brain cognitive functions. This system is portable, and works with a small rechargeable battery; thus, it may be used for bedside monitoring. In our CW-NIRS system, we used 3 multi-wavelength LEDs and 8 photodiodes (with built-in amplifiers) resulting in 12 channels (voxels). The collected signals of these 12 channels, at a sampling rate of 15 Hz, can be used for 2D image reconstruction to monitor functional brain activity. All LEDs and photodiodes are placed on a flexible printed circuit board (PCB), which covers the forehead to measure hemodynamic response of the prefrontal cortex. We also developed a software in MATLAB for analysis of optical signals recorded by our CW-NIRS system. This software provides 2D image reconstruction and monitoring of changes in concentration of oxygenated ([HbO2]) and deoxygenated ([HbR]) hemoglobin as well as the total hemoglobin ([HbT]) for the 12 channels over the prefrontal cortex (forehead). The software has also an embedded statistical analysis option for analyzing the collected signals and displaying the results. The developed CW-NIRS system was evaluated on 14 individuals (24±3 years old) on two common cognitive tasks: verbal fluency task (VFT) and color distinction task (CDT). In both tests, we observed that as the cognitive task begins [HbO2] and [HbT] increase and [HbR] decreases, after a few seconds delay. Furthermore, at the end of the tasks as subjects close their eyes in the second rest state, all three hemodynamic signals converge toward baseline ([HbO2] and [HbT] decrease and [HbR] increases). Also, the difference between hemodynamic signals at the rest state and task state was highly significant (p < 9.95e-11) in all 12 channels and in both cognitive tasks. The results confirm the ability of the designed CW-NIRS system to detect functional brain activities.

The heating curves for a number of different materials, including metals and non-metals, were observed while being irradiated with a beam from a C02 gas laser. The radiant energy spectrum emitted by the materials was measured and recorded, and from this data the heating and cooling rates of the materials were determined. Infrared measurements in the 3 to 5 micron and 8 to 14 micron regions were performed using two Barnes Spectral-Master Radiometers. Data was recorded with both stationary and moving target materials to determine the effect of airflow on the heating and cooling characteristics of the materials. The observed initial heating curve for the solid materials up to the melting point are compared with a theoretical model. The procedure for calibration of the equipment and for data collection is also contained in this thesis.These measurements are important because the experimental conditions closely approximate realistic environmental conditions for materials which are used in different types of aircraft during flight.

The synthesis of the catenane components, a dithiol and a cyclophane, are described using previously reported methods. 1-3 The preparation techniques used to obtain a self-assembled dithiol monolayer and a self-assembled catenane monolayer from dilute solution onto a gold's surface are also reported. Grazing angle reflectance infrared spectroscopy was used to characterize the selfassembled dithiol and catenane monolayers. The infrared spectra revealed evidence for the existence of the dithiol monolayer and possible evidence for the existence of the catenane monolayer. A catenane transmission film spectrum was obtained to provide evidence for the existence of the catenane itself. When the transmission and the monolayer spectra were compared, shifts in a few of the absorption bands revealed some association between the dithiol and the cyclophane. / Department of Chemistry

The potential of different spectroscopic techniques for evaluating potato (Solanum tuberosum L.) quality was investigated. Spectral data in the wavelength range of 400-1750 nm were used to develop quality prediction models. The Partial Least Squares (PLS) regression was used for predicting the water content in potato samples. Water content was predicted with R2 ≥ 0.938. / A further study was conducted to find the best wavelengths for predicting water content using two methods, PLS and multiple linear regression. Wavelength ranges of 910-1020, 1129-1211, 1363-1403 nm were selected for samples without skin, while 700-900, 930-1050, 1100-1300, 1400-1550 nm were selected for samples with-skin. Weight prediction models were established using the predicted water content. / Visible spectroscopy was used for classifying shriveled and non-shriveled potatoes. The wavelength ranges best suited to such a classification were those of 442-452, 456-466, 641-651, and 684-694 nm, with accuracies as high as 94.28% and as low as 80%.

Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 194-200). / Microfiche. / xiv, 200 leaves, bound ill. 29 cm

Thesis (MAppSc)--University of South Australia, 2000