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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
281

Infrared characterization of a self-assembled catenane monolayer on gold

Girot, Christine Stoll January 1996 (has links)
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
282

Infrared microspectroscopy of focally elevated creatine in brain tissue from amyloid precursor protein (APP) transgenic mice

Gallant, Meghan 18 January 2008 (has links)
Infrared microspectroscopy has been used to survey Alzheimer’s diseased brain tissue from a transgenic mouse model of the disease. Alzheimer’s disease is the leading cause of dementia among the elderly and is characterized by β-amyloid plaque deposition,neurofibrillary tangles, inflammation, and disturbed energy metabolism in the brain. Both the TgCRND8 and Tg19959 mouse models of the disease develop Alzheimer’s disease pathology beginning at approximately 3 months of age. Infrared microspectroscopy allows analysis of untreated, flash frozen tissue samples, at micron level spatial resolution, and was used in this study to examine creatine deposits in the Alzheimer’s diseased brain. Creatine is central to cellular energetics and plays an important role in proper brain function. The hippocampi of 7 pairs of transgenic mice and their littermate controls were mapped using infrared microspectroscopy and the results were analyzed for creatine levels and levels of β-sheet, indicative of the presence of β-amyloid plaques. Creatine was found to be focally elevated in the transgenic mice, as compared to their littermate controls but was not co-localized with β-amyloid plaques. Further surveys of serial sections from one transgenic mouse showed the 3-dimensional distribution of creatine within the sample. Focally elevated creatine may be a marker of the disease process, indicative of disturbed energy metabolism or inflammatory response to the disease progression.
283

Long wavelength near-infrared hyperspectral imaging for classification and quality assessment of bulk samples of wheat from different growing locations and crop years

Sivakumar, Mahesh 01 September 2011 (has links)
A platform technology is identified for grain handling facilities to improve grading and determine non-destructively different quality parameters of wheat. In this study, a near-infrared (NIR) hyperspectral imaging system was used to scan four wheat classes namely, Canada Western Red Spring (CWRS), Canada Prairie Spring Red (CPSR), Canada Western Hard White Spring (CWHWS), and Canada Western Soft White Spring (CWSWS) that were collected from across various growing regions in Manitoba, Saskatchewan, and Alberta in 2007, 2008, and 2009 crop years. A database of the near-infrared (NIR) hyperspectral image cubes of bulk samples of four wheat classes at three moisture levels for each class was created. These image cubes were acquired in the wavelength region of 960-1700 nm with 10 nm intervals. Wheat classification was done using the non-parametric statistical and a four-layer back propagation neural network (BPNN) classifiers. Average classification accuracies of 93.1 and 83.9% for identifying wheat classes using the linear discriminant analysis (LDA) and quadratic discriminant analysis (QDA), respectively, were obtained for two-class identification models that included variations of moisture levels, growing locations, and crop years of samples. In the pair-wise moisture discrimination study, near-perfect classifications were achieved for wheat samples which had difference in moisture levels of about 6%. The NIR wavelengths of 1260-1380 nm had the highest factor loadings for the first principal component using the principal components analysis (PCA). A four-layer BPNN classifier was used for two-class identification of wheat classes and moisture levels. Overall average pair-wise classification accuracies of 83.7% were obtained for discriminating wheat samples based on their moisture contents. Classification accuracies of 83.2, 75.4, 73.1%, on average, were obtained for identifying wheat classes for samples with 13, 16, and 19% moisture content (m.c.), respectively. Ten-factor partial least squares regression (PLSR) and principal components regression (PCR) models were developed using a ten-fold cross validation for prediction. Prediction performances of PLSR and PCR models were assessed by calculating the estimated mean square errors of prediction (MSEP), standard error of cross-validation (SECV), and correlation coefficient (r). Overall, PLSR models demonstrated better prediction performances than the PCR models for predicting protein contents and hardness of wheat.
284

Visible and near-infrared spectroscopic analysis of potatoes

Singh, Baljinder January 2005 (has links)
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%.
285

Étude des alcanes liquides par une méthode de spectroscopie infrarouge utilisant des sondes moléculaires = Studies of liquid alkanes by an infrared spectroscopic method using molecular probes / Studies of liquid alkanes by an infrared spectroscopic method using molecular probes.

Richon, Dominique January 1977 (has links)
No description available.
286

Near-infrared spectroscopy of luminous infrared galaxies

Goldader, Jeffrey Dale January 1995 (has links)
Thesis (Ph. D.)--University of Hawaii at Manoa, 1995. / Includes bibliographical references (leaves 194-200). / Microfiche. / xiv, 200 leaves, bound ill. 29 cm
287

Reduction of the uncertainty in the Australian near infrared responsivity units /

Atkinson, Errol G Unknown Date (has links)
Thesis (MAppSc)--University of South Australia, 2000
288

Reduction of the uncertainty in the Australian near infrared responsivity units /

Atkinson, Errol G Unknown Date (has links)
Thesis (MAppSc)--University of South Australia, 2000
289

Spectroscopic studies of gas phase ion-neutral interactions

Loh, Zöe Miranda Unknown Date (has links) (PDF)
Gas phase experimental and computational investigations are described for F--H2 and the halide-methane complexes and clusters, F--(CH4)n and Cl--(CH4)n. Vibrational predissociation spectroscopy in conjunction with tandem mass spectrometry are used to obtain mid-infrared spectra of each complex in the ligand’s hydrogen stretch region. Ab initio calculations are used to predict structures, binding energies and vibrational frequencies and intensities. By examining the changes in both the vibrational frequencies and intensities of the neutral moiety upon complexation with the anion, and comparing these with the theoretical predictions, structures are able to be inferred. (For complete abstract open document)
290

The automatic eye alignment of an infrared optometer

Taylor, David Glenville January 2009 (has links)
The ability of the human eye to change its overall refractive power so that people can focus on objects both far and near is termed accommodation. Research into how the eye automatically changes its accommodation, demands an instrument capable of tracking the accommodation with fine resolution and adequate corner frequency. An instrument capable of tracking the ocular accommodation is called an optometer. Reports of earlier optometers show that optometers using the older Scheiner principlecan have the required precision and dynamics required to track the micro fluctuations accommodation. However optometers using the Scheiner principle require precise alignment to the patient’s pupil to be maintained throughout the measurement time. Previous optometers have used the radiation reflected from the patient’s cornea (calledthe corneal reflection) to initially align the optical axis of the optometer to the centre of the patient’s pupil. Since the Scheiner principle optometer uses radiant energy reflected from the patient’s retina to make a refractive measurement, the idea of using this same radiant energy for patient alignment is investigated. Earlier optometers have blocked the corneal reflection from reaching the photodetectors for the retinal reflection using a small fixed light stop. Since it is not possible to use a fixed light stop if the retinal reflection is used for alignment, the feasibility of using crossed linear polarizers is experimentally evaluated. The results showed that about78% of the radiant energy reflected from the front lens of an artificial eye could be eliminated using crossed linear polarizers. Whether the Scheiner principle measurement of refraction of an artificial eye could be done with 78% of the front lens (corneal) reflection removed was investigated. The results were not conclusive. There was not a measureable indication of when the refraction of the experimental optometer matched that of the artificial eye. The experimental optometer system attempts to use a servo controlled mirror system to move the optical axis of the optometer so that it coincides with the optical axis of an artificial eye. The design, development and testing of the mirror system is described. The mirror system enables the optometer to perform a two dimensional scan over the pupil plane of the patient’s eye or an artificial eye. During the scanning, the total radiant power reflected can be measured. For the optometer to be aligned using radiation reflected from the retina, a scan of the pupil plane of should reveal the pupil boundaries. This was experimentally demonstrated to work. Unfortunately time limitations did not permit further development of an automatic eye alignment and tracking system.

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