Thesis (M.S.)--University of Wisconsin--Madison, 1982. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 64-68).

Inaug.-diss.--Jena. / Cover title.

Inaug.-diss.--Jena. / Cover-title.

La spectroscopie RMN a été utilisée de longue date dans l’étude des élastomères, en particulier les expériences 2D pour l’élucidation structurale. Cependant, celles-ci souffrent de longues durées d’acquisition. Parmi les nombreuses approches envisagées pour pallier cela, la RMN 2D ultrarapide (UF) offre une accélération drastique. L’objectif de cette thèse est de repousser les limites de cette technique, et d’évaluer son applicabilité à l’étude d’élastomères. L’optimisation des paramètres expérimentaux, via des calculs théoriques et simulations, nous a permis d’augmenter significativement la sensibilité des expériences UF à double quanta (UF-DQS), diminuant ainsi leur limite de détection. De plus, nous avons montré que les performances analytiques de l’UF-DQS en font un outil pertinent pour l’analyse d’échantillons complexes. Grâce à l’introduction et l’optimisation d’un découplage adiabatique, nous avons rendu possible l’acquisition d’un spectre UF-HSQC complet en quelques minutes. Malgré leur sensibilité limitée, de telles expériences peuvent être une alternative à la HSQC conventionnelle pour l’élucidation structurale. Nous avons implémenté pour la première fois la version ultrarapide d’expériences de RMN du solide. Leur rapidité pourrait particulièrement bénéficier aux études structurales par RMN du solide nécessitant l’acquisition de nombreux spectres 2D, ainsi qu’à l’étude d’échantillons avec de longs temps de relaxation longitudinale. L’accessibilité de l’UF aux non-spécialistes a été facilitée par l’automatisation des étapes de paramétrage et de calibrage. Enfin, une étude préliminaire d’applicabilité des méthodes UF à l’étude d’élastomères est présentée. / NMR spectroscopy has been used for decades to study elastomeric samples, in particular 2D experiments for their structural elucidation. However, the latter suffer from long acquisition times. Among the numerous approaches investigated to alleviate it, ultrafast (UF) 2D NMR offers a drastic acceleration. The driving force of this PhD project is to push the boundaries of the UF methodology and evaluate its applicability to the study of elastomers. Thanks to a fine tuning of experimental parameters through theoretical studies and simulations, we significantly enhanced the sensitivity of UF double quantum experiments (UF-DQS), thus lowering their limit of detection. The evaluation of their analytical performance demonstrates their relevance as a tool for the analysis of complex mixtures. Through the optimization of adiabatic decoupling schemes, we could record full-range UF-HSQC spectra in a few minutes. Despite its limited sensitivity, optimized UF-HSQC can be used for structural elucidation, as an alternative to conventional HSQC. We also report the first implementation of solid-state NMR pulse sequences in an ultrafast fashion. Such experiments will prove useful for structural studies by solid-state NMR requiring arrays of 2D spectra as well as for applications to samples with long longitudinal relaxation times. Our efforts have also been geared towards the accessibility of the UF methodology to non-specialists. To this end, a new implementation protocol has been released, including automatic parametrization of the experiments and automatic calibration of the spectrum. Finally, we report a preliminary study on the applicability of UF methods to the study of elastomers.

Introduction: The purposes of this study were several. The first was to establish a mean value for the crown-to-root angle, or collum angle (CA), for maxillary central incisors in Class I normal occlusions. The second was to create a new crown-to-root angle based on anatomic points, the labial crown-root angle (LCRA), and correlate it with the CA for Class I normal occlusions and Class II division 2 malocclusions. Third, torque values were measured for maxillary central incisors using these anatomic points, and mean values were calculated for Class I normal occlusions and Class II division 2 malocclusions. Finally, mean values for CA and LCRA were analyzed for Class I normal occlusions and Class II division 2 malocclusions to detect differences between the two groups. Methods: 51 Class I normal samples and 42 Class II division 2 samples who met the inclusion criteria were studied cephalometrically. Relevant landmarks were placed, analyzed for reliability, and recorded for the measurements of interest. Results: The mean CA for Class I normal occlusions was not statistically different from zero (p= .0657). A strong increasing correlation between CA and LCRA was found for all samples (Pearson's correlation coefficient = 0.88, p < .0001). Mean torque values for Class I normal occlusions and Class II division 2 malocclusions were statistically different (3.95±10.85 degrees vs. 12.54±5.82 degrees, p < .0001). The mean CA for Class I normal occlusions and Class II division 2 malocclusions were statistically different (4.29±5.77 degrees vs. 1.78±3.94 degrees, p = .0178). The mean LCRA for Class I normal occlusions and Class II division 2 malocclusions were statistically different (31.60±4.24 degrees vs. 34.84±5.95 degrees, p = .00037). Conclusions: The mean CA in Class I normal occlusions is not statistically different from zero degrees. The LCRA is strongly correlated with the CA in both Class I normal occlusions and Class II division 2 malocclusions. The mean maxillary central incisor torque values for Class I normal occlusions is similar to that found in bracket prescriptions currently offered. Patients with Class II division 2 malocclusion exhibit statistically higher mean CA and LCRA values than patients with Class I ideal occlusion.

Purpose: To define initial hard and soft tissue convexity necessary for profiles to consistently improve after mandibular advancement and to assess if pre-surgical lower incisor inclination (IMPA) affects profile change. Methods: 20 general public, 20 orthodontists, and 20 oral surgeons used a Likert scale to rate attractiveness of before and after treatment profiles of mandibular advancement patients. Spearman’s correlation tested for relationships between amount of profile change and varying ANB, profile angle and pre-surgical IMPA. Wilcoxon test compared extraction and non-extraction profile changes. Results: There was a tendency for inverse correlations between profile change and profile angle, but was not statistically significant any of the 3 groups. There was a tendency for positive correlations between profile change and ANB, but was considered significant only for orthodontists. Orthodontists, oral surgeons and the general public found profiles consistently improved when profile angles were ≤159º, ≤158º and ≤157º, respectively. Orthodontists and oral surgeons found profiles consistently improved when ANB angles were ≥5.5º and ≥6.5º, respectively. Profile worsening increases 2.6 to 5.0 times when profile angles exceeded thresholds, and 4.5 to 7.9 times when ANB angles were less than thresholds. No difference in IMPA or profile change in extraction and non-extraction groups. Conclusion: Extractions are not predictive of a greater surgical profile change. Pre-treatment profile angles <160º and ANB >6º are necessary for consistent improvements after surgery. / October 2006

Purpose: To define initial hard and soft tissue convexity necessary for profiles to consistently improve after mandibular advancement and to assess if pre-surgical lower incisor inclination (IMPA) affects profile change. Methods: 20 general public, 20 orthodontists, and 20 oral surgeons used a Likert scale to rate attractiveness of before and after treatment profiles of mandibular advancement patients. Spearman’s correlation tested for relationships between amount of profile change and varying ANB, profile angle and pre-surgical IMPA. Wilcoxon test compared extraction and non-extraction profile changes. Results: There was a tendency for inverse correlations between profile change and profile angle, but was not statistically significant any of the 3 groups. There was a tendency for positive correlations between profile change and ANB, but was considered significant only for orthodontists. Orthodontists, oral surgeons and the general public found profiles consistently improved when profile angles were ≤159º, ≤158º and ≤157º, respectively. Orthodontists and oral surgeons found profiles consistently improved when ANB angles were ≥5.5º and ≥6.5º, respectively. Profile worsening increases 2.6 to 5.0 times when profile angles exceeded thresholds, and 4.5 to 7.9 times when ANB angles were less than thresholds. No difference in IMPA or profile change in extraction and non-extraction groups. Conclusion: Extractions are not predictive of a greater surgical profile change. Pre-treatment profile angles <160º and ANB >6º are necessary for consistent improvements after surgery.

Purpose: To define initial hard and soft tissue convexity necessary for profiles to consistently improve after mandibular advancement and to assess if pre-surgical lower incisor inclination (IMPA) affects profile change. Methods: 20 general public, 20 orthodontists, and 20 oral surgeons used a Likert scale to rate attractiveness of before and after treatment profiles of mandibular advancement patients. Spearman’s correlation tested for relationships between amount of profile change and varying ANB, profile angle and pre-surgical IMPA. Wilcoxon test compared extraction and non-extraction profile changes. Results: There was a tendency for inverse correlations between profile change and profile angle, but was not statistically significant any of the 3 groups. There was a tendency for positive correlations between profile change and ANB, but was considered significant only for orthodontists. Orthodontists, oral surgeons and the general public found profiles consistently improved when profile angles were ≤159º, ≤158º and ≤157º, respectively. Orthodontists and oral surgeons found profiles consistently improved when ANB angles were ≥5.5º and ≥6.5º, respectively. Profile worsening increases 2.6 to 5.0 times when profile angles exceeded thresholds, and 4.5 to 7.9 times when ANB angles were less than thresholds. No difference in IMPA or profile change in extraction and non-extraction groups. Conclusion: Extractions are not predictive of a greater surgical profile change. Pre-treatment profile angles <160º and ANB >6º are necessary for consistent improvements after surgery.

Thèse (M.Med.Exp.) -- Université Laval, extensionné à l'Université du Québec à Chicoutimi, 1999. / Bibliogr.: f. 70-79. Document électronique également accessible en format PDF. CaQCU

The design, analysis, and performance of a small-angle scatterometer are presented. The effects of the diffraction background, geometrical aberrations and system scatter at the small-angles are separated. Graphs are provided that quantify their contribution. The far-field irradiance distributions of weakly truncated and untruncated Gaussian beams are compared. The envelope of diffraction ringing is shown to decrease proportionately with the level of truncation in the pupil. Spherical aberration and defocus are shown to have little effect on the higher-order diffraction rings of Gaussian apertures and as such will have a negligible effect on most scatter measurements. A method is presented for determining the scattered irradiance level for a given BRDF in relation to the peak irradiance of the point spread function. A method of Gaussian apodization is presented and tested that allows the level of diffraction ringing to become a design parameter. Upon sufficient reduction of the diffraction background, the scattered light from the scatterometers' primary mirror is seen to be the limiting component of the small-angle instrument profile. The scatterometer described was able to make a meaningful measurement close enough to the specular direction at 0.6328μm in order to observe the characteristic height and width of the scatter function. This allowed the rms roughness and autocorrelation length of the surface to be determined from the scatter data at this wavelength. The inferred rms roughness agreed well with an independent optical profilometer measurement of the surface. The BRDF of the samples were also measured at 10.6μm. The rms roughness inferred from this scatter data did not agree with the other measurements. The BRDF did not scale in accordance with the scaler diffraction theory of microrough surfaces. The scattering in the visible was dominated by the effects of surface roughness whereas the scattering in the far-infrared was apparently dominated by the effects of contaminants and surface defects. The model for the surface statistics is investigated. A K₀ (modified Bessel function) autocorrelation function is shown to predict the scattered light distribution of these samples much better than the conventional negative-exponential function. Additionally, a sampling theory is developed that addresses the negative-exponentially correlated output of lock-in amplifiers, detectors, and electronic circuits in general. It is shown that the optimum sampling rate is approximately one sample per time constant and at this rate the improvement in SNR is √(N/2) where N is the number of measurements.