<p>Compact diode-pumped solid-state lasers (DPSSL) arecontinuously replacing traditional gas lasers as well asenabling completely new technology. However, compact and costefficient designs are required to satisfy end-user demands. Theaim of this thesis was therefore to investigate novel laserdesigns for given applications considering these demands. In alarge part of the thesis work, nonlinear optics were employedto realize laser wavelengths where there was no appropriatelaser transition available.</p><p>Besides other nonlinear crystals such as BBO, LBO and KTP,periodically poled KTP played an important role in this thesiswork. Its unique properties regarding up conversion processeswere exploited, thus supplying a broadened view over itspotential and limitations.</p><p>This thesis places emphasis on practical concerns, mainlyrelated to real applications. It gives solutions to the beamshaping of laser diodes, covers the simulation and the designof laser dynamics as well as laser performance and describesthe sources of laser output degradation and damage mechanisms.Novel infrared lasers were designed and multiple intra-cavity,external cavity and non-resonant multi-pass frequencyconversion schemes were successfully employed and optimized.These produced red, orange, green, blue and ultraviolet outputfor various applications like spectroscopy, micro machining andwriting of fiber Bragg gratings.</p><p><b>Keywords:</b>diode-pumped solid-state lasers, nonlinearoptics, frequency conversion,</p>

Predicting tenderness in today's beef supply could be advantageous to packers and consumers. In this study (n = 1,137 carcasses), visible-near-infrared, electrical impedance, pH and Minolta CIE L*, a*, and b* color space values were examined as predictors of beef 1, 7, and 14 d Warner-Bratzler (N) or Slice Shear (N) force values as estimators of beef tenderness. Visible-NIR at 350 to 1830 nm, electrical impedance, and color space values were taken at the beef packing plant, along with carcass data. Strip loins were transported to Texas A & M University where pH was taken. Six steaks were taken from the anterior end of the strip loin and randomly assigned to either Warner-Bratzler shear force (WBSF) after 1, 7, or 14 days, or Slice shear force (SSF) after 1, 7, and 14 days of post-harvest aging at 2 degrees C. Shears were taken on assigned days. Shear force values were highly correlated with each other (r = 0.37 to 0.56 for WBSF and r = 0.75 to 0.78 for SSF) (P < 0.05). Within the independent variables, reflectance values for mid-range wavelengths (562nm-1193nm) were found to be most highly correlated with the dependent variables (P < 0.05). pH and color spaces values were more highly correlated (P < 0.05) to slice shears values then to Warner-Bratzler shears force values. Electrical impedance was the least significant with r values of 0.00 to 0.14. When Visble-NIR reflectance values were used in stepwise regression equations to predict 1, 7, or 14 d WBSF or 1, 7, or 14 d SSF, prediction equations for 14 d WBSF and SSF had the highest R^2 (0.14 and 0.36, respectively). Stepwise regression equations that included pH and color space values had the highest R^2 for 7 d WBSF and 1 d SSF (0.22 and 0.28, respectively). Electrical impedance alone in a stepwise regression equation had the highest R^2 for 1 and 14 d WBSF and 1 and 7 d SSF (0.02 and 0.03, respectively). Stepwise regression equations that included pH, color space values, and electrical impedance had the highest R^2 for 7 d WBSF and 14 d SSF (0.25 and 0.24, respectively). When pH, color space values, electrical impedance, and Visible-NIR were used, 7 d WBSF and 1 d SSF had the highest R^2 (0.38 and 0.34, respectively). Stepwise regression equations that included pH, color space values, and Visible-NIR had the highest R^2 for 7 d WBSF and 14 d SSF (0.30 and 0.44, respectively). For predicting 14 d Warner-Bratzler shear force, a R^2 of 0.20 was found using Visible-NIR, pH and color space values. When used, the partial least squares equation predicted tenderness with an 85 percent success rate. For predicting 14 d Slice shear forces, a R^2 of 0.40 was found. When used, the partial least squares equation had a 100 percent success rate of predicting those steaks found tender to be tender for Slice shear force. There was an 85 percent success rate for predicting 14 d Warner-Bratzler shear forces. Both equations still had little to no success in predicting tough steaks. The Visible-NIR can successfully predict tenderness

No description available.

The on-going calibration and validation of visible satellite imagery remains a core activity of the scientific community in pursuit of high quality data characterising the oceanic chlorophyll field, providing input to models assessing primary productivity and the potential role of the oceans in climatic regulation. This work serves to examine the operational characteristics of semi-analytical algorithms that are designed to derive key optical properties from space born observations of ocean colour. The collection of water samples contemporaneously with precision profiled radiometry conforming to similar spectral bands to those of the NASA Sea Viewing Wide Field of view Sensor (SeaWiFS) was planned and executed, with appropriate field sampling techniques developed in accordance with the SeaWiFS Ocean Optics protocols (Mueller and Austin, 1995). Data were collected during extensive fieldwork sampling at a near coastal survey site and during two deep Atlantic research programmes. Historical and recently developed algorithms designed to retrieve the diffuse attenuation coefficient at 490nm and chlorophyll-a pigment concentrations from upwelling radiances were applied to the optical data, to compare the mathematically retrieved in-water properties with the values measured in-situ. The radiometric data were then used to generate general and local algorithm modifications to assess possible differences in the mathematically retrieved values. Statistical analyses of the errors in mathematical retrieval of in-water properties identified stmctured variability resulting from the empirical approach to algorithm generation, supporting the point of view that locally constrained algorithms provide a method of achieving significantly improved results. The problems associated with the derivation of semi-analytical algorithms are then discussed and errors analysed. The new algorithms generated here are found to compare well with their source data and with work by other investigators. Systematic variability was found within the data sets and the affect this has on the determinations is discussed. It is suggested that data users be afforded details of the equations employed in the production of readily available remote sensing products, placing them in a position where they are better able to assess the data in the context of their work.

The motivation for this thesis was to study chemical and dynamical processes in the Arctic stratosphere, using data from two ground-based spectrometers (GBSs). The GBSs took atmospheric trace gas measurements at the Polar Environment Atmospheric Research Laboratory (PEARL), which is located at Eureka, Nunavut, Canada (80.05°N, 86.42°W) and operated by the Canadian Network for the Detection of Atmospheric Change. The University of Toronto GBS took measurements at Eureka on a campaign basis from 1999 2011. The PEARL GBS was installed permanently at Eureka in 2006 and has taken measurements during the sunlit part of the year since then. GBS and other ground based ozone and NO2 column measurements were compared with Atmospheric Chemistry Experiment (ACE) and Optical Spectrograph and Infra Red Imaging System (OSIRIS) satellite measurements above Eureka. Ozone from all instruments agreed within 9.2%, while NO2 from most instruments, including the GBS, agreed to within 20%. On 1 August 2008, a solar eclipse of 98% totality passed over Eureka. GBS NO2 increased to 1.84 times normal levels. This agrees with a ratio of 1.91 that was calculated using a photochemical model, adjusted for reduced sunlight during the eclipse. In spring/winter 2011, up to 47% (250 DU) ozone loss was calculated using GBS and modeled passive ozone. This was the largest ozone loss in the 11 year GBS measurement record. GBS OClO was elevated, indicating chlorine activation and NO2 was low, suggesting denitrification. GBS, satellite, and chemical transport model data were used to investigate the 2011 vortex breakup. NOx transport led to middle stratosphere ozone loss within an anticyclone. Furthermore, isolated, or “frozen-in”, vortex and lower-latitude airmasses were observed following the vortex breakup. Stratospheric BrO was retrieved from spring 2008 GBS zenith sky measurements, using an optimal estimation technique. GBS BrO was compared with OSIRIS and Ozone Monitoring Instrument (OMI) satellite data. Discrepancies are partly attributed to bromine explosions in the boundary layer. New off axis GBS measurements taken in spring 2010 are sensitive to boundary layer bromine. The combination of GBS stratospheric and tropospheric BrO measurements will be useful for future estimates of the Arctic bromine budget.

The motivation for this thesis was to study chemical and dynamical processes in the Arctic stratosphere, using data from two ground-based spectrometers (GBSs). The GBSs took atmospheric trace gas measurements at the Polar Environment Atmospheric Research Laboratory (PEARL), which is located at Eureka, Nunavut, Canada (80.05°N, 86.42°W) and operated by the Canadian Network for the Detection of Atmospheric Change. The University of Toronto GBS took measurements at Eureka on a campaign basis from 1999 2011. The PEARL GBS was installed permanently at Eureka in 2006 and has taken measurements during the sunlit part of the year since then. GBS and other ground based ozone and NO2 column measurements were compared with Atmospheric Chemistry Experiment (ACE) and Optical Spectrograph and Infra Red Imaging System (OSIRIS) satellite measurements above Eureka. Ozone from all instruments agreed within 9.2%, while NO2 from most instruments, including the GBS, agreed to within 20%. On 1 August 2008, a solar eclipse of 98% totality passed over Eureka. GBS NO2 increased to 1.84 times normal levels. This agrees with a ratio of 1.91 that was calculated using a photochemical model, adjusted for reduced sunlight during the eclipse. In spring/winter 2011, up to 47% (250 DU) ozone loss was calculated using GBS and modeled passive ozone. This was the largest ozone loss in the 11 year GBS measurement record. GBS OClO was elevated, indicating chlorine activation and NO2 was low, suggesting denitrification. GBS, satellite, and chemical transport model data were used to investigate the 2011 vortex breakup. NOx transport led to middle stratosphere ozone loss within an anticyclone. Furthermore, isolated, or “frozen-in”, vortex and lower-latitude airmasses were observed following the vortex breakup. Stratospheric BrO was retrieved from spring 2008 GBS zenith sky measurements, using an optimal estimation technique. GBS BrO was compared with OSIRIS and Ozone Monitoring Instrument (OMI) satellite data. Discrepancies are partly attributed to bromine explosions in the boundary layer. New off axis GBS measurements taken in spring 2010 are sensitive to boundary layer bromine. The combination of GBS stratospheric and tropospheric BrO measurements will be useful for future estimates of the Arctic bromine budget.

This thesis presents the synthesis and characterization of copper oxide nano photocatalyst for wastewater purification using visible light. The presented copper oxide nano material can serve as a low-cost and green technology for environmental applications. Uniform cubic, octahedral and rhombic dodecahedral Cu2O nano crystals with a size of 300-600 nm were synthesized using a simple hydrothermal method. The rhombic dodecahedral Cu2O nano crystals are highly active when driven by low-power white LEDs as a light source. In comparison with other reported photocatalysts, the Cu2O nano crystals in this work show a much higher reaction rate and lower electrical energy per order. The reaction rate and photoefficiency are found to be highly correlated with the irradiated photon flux. The surface termination and facet orientation of Cu2O nano particles were accurately tuned by adjusting the amount of hydroxylamine hydrochloride and surfactant. It is found that Cu2O nano particles with Cu-terminated (110) or (111) surfaces show high photocatalytic activity, while other exposed facets show poor reactivity. The density functional theory simulations confirm that the sodium dodecyl sulfate surfactant can lower the surface free energy of Cu-terminated surfaces, increasing the density of exposed Cu atoms at the surfaces, and thus benefiting the photocatalytic activity. It also shows that the poor reactivity of Cu-terminated Cu2O (100) surface is due to the high energy barrier of holes at the surface region. Amorphous CuxO nano flakes with a thickness of 10 to 50 nm were prepared through the dye-assisted transformation of rhombic dodecahedral Cu2O nano crystals under facile hydrothermal condition. The amorphous CuxO nano flake consists of a combination of Cu(I) and Cu(II) with a ratio close to 1:1. It shows enhanced photocatalytic reactivity towards the degradation of methyl orange compared to rhombic dodecahedral Cu2O nano crystals with all active (110):Cu facets. The chemical composition and architecture remain the same after repeating degradation tests. The high surface-to-volume ratio contributes to its better photocatalytic performance while its low surface energy calculated by the density functional theory simulations explains its improved stability. The as-obtained photocatalysts are able to degrade a wide range of aromatic organics including toluene, chlorobenzene and nitrobenzene effectively. We also demonstrate the capability of decontaminating a wide range of aromatic organics in industrial wastewater that comes from an oil company.

Neste trabalho foram empregados os métodos hidro e solvotérmico para sintetizar três diferentes catalisadores à base de bismuto (Bi2WO6, BiOI e BiVO4), visando aplicação em fotocatálise heterogênea sob radiação visível. Foram investigadas as influências do tempo de síntese, da calcinação, da adição de polivinilpirolidona (PVP) e do tipo de solvente usado durante a síntese sobre a morfologia, cristalinidade, área superficial específica e band gap das amostras. Os catalisadores foram caracterizados por microscopia eletrônica de varredura (MEV), espectroscopia de refletância difusa (ERD), difração de Raios-X (DRX) e adsorção de N2. Para avaliar a atividade fotocatalítica das amostras sintetizadas foram realizados experimentos em um reator batelada agitado, com o catalisador em suspensão e uma lâmpada de LED como fonte de radiação visível. As moléculas testes escolhidas foram o corante rodamina B, para determinação das amostras com maior atividade e, posteriormente, o fármaco prednisolona, sendo então estudados a influência da concentração de catalisador e do pH inicial do meio reacional. Foram realizados, também, ensaios de toxicidade com o organismo Lactuca sativa – sementes de alface, para avaliar a toxicidade da prednisolona pura, da mistura água e catalisador de BiOI e das alíquotas provenientes da reação de degradação da prednisolona após diferentes tempos. As amostras de Bi2WO6 apresentaram boa cristalinidade e semelhanças morfológicas apesar dos diferentes tratamentos. As amostras de BiOI, por sua vez, apresentaram diferenças significativas de morfologia, de microesferas para microplacas, quando foi feita a mudança de solvente e a amostra de BiVO4 apresentou um formato de paralelepípedo. Nos testes fotocatalíticos com a rodamina B, o catalisador que se mostrou mais ativo foi o BiOI cuja síntese continha PVP e etilenoglicol (kap = 0,0207 min-1) e o BiVO4 foi o que apresentou a menor atividade (kap = 0,0013 min-1). Na degradação da prednisolona, a maior taxa de degradação foi obtida com 1 g L-1 de catalisador e no pH natural do fármaco, 6,8. Os ensaios de toxicidade revelaram que nem a prednisolona nem a mistura água e catalisador são tóxicas para as sementes de alface, as alíquotas provenientes da reação, porém, tiveram um aumento de sua toxicidade com o aumento do tempo de reação. / In this work, solvo and hydrothermal methods were applied to synthesize three types of bismuth catalysts (Bi2WO6, BiOI and BiVO4) aiming to the apply it in heterogeneous photocatalysis under visible light. Were investigated the influences of reaction time, calcination, addition of poly (vinyl pyrrolidone) (PVP) and the solvent type during synthesis on their morphology, crystallinity, surface area and band gap. The catalysts were characterized by scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), X-ray powder diffraction (XRD) and nitrogen adsorption/desorption. To evaluate photocatalytic activity of the synthesized samples, experiments were carried out in a stirred batch reactor, with the catalyst in suspension and a LED lamp as a source of visible light. The test molecules chosen were the rhodamine B dye for determination of the samples with higher activity and subsequently the drug prednisolone, and then was studied the effect of catalyst concentration and initial pH of the reaction medium. Toxicity tests were also perfomed with organism Lactuca sativa – lettuce seeds, to the toxicity of pure prednisolone, water and BiOI catalyst mixture and aliquots from prednisolone degradation after different reaction times. As a result, the Bi2WO6 samples presented good crystallinity and morphological similarities despite having undergone different treatments. The BiOI catalysts presented a significant difference in morphology, microspheres to microplates, when changed the solvent, while the BiVO4 sample presented a parallelepiped shape. In the photocatalytic tests with rhodamine B, the catalyst with the highest activity was BiOI, containing PVP and ethylene glycol (kap = 0.0207 min-1) in its synthesis, and the BiVO4 was the catalyst with the lowest activity (kap = 0.0013 min-1). In the prednisolone degradation, the highest degradation rate was obtained with 1 g L-1 of catalyst and natural pH of the drug, 6.8. The toxicity tests showed that neither prednisolone nor water and catalyst mixture are toxic to lettuce seeds, aliquots from reaction, however, had an increase in their toxicity with increasing reaction time.

Neste trabalho foram empregados os métodos hidro e solvotérmico para sintetizar três diferentes catalisadores à base de bismuto (Bi2WO6, BiOI e BiVO4), visando aplicação em fotocatálise heterogênea sob radiação visível. Foram investigadas as influências do tempo de síntese, da calcinação, da adição de polivinilpirolidona (PVP) e do tipo de solvente usado durante a síntese sobre a morfologia, cristalinidade, área superficial específica e band gap das amostras. Os catalisadores foram caracterizados por microscopia eletrônica de varredura (MEV), espectroscopia de refletância difusa (ERD), difração de Raios-X (DRX) e adsorção de N2. Para avaliar a atividade fotocatalítica das amostras sintetizadas foram realizados experimentos em um reator batelada agitado, com o catalisador em suspensão e uma lâmpada de LED como fonte de radiação visível. As moléculas testes escolhidas foram o corante rodamina B, para determinação das amostras com maior atividade e, posteriormente, o fármaco prednisolona, sendo então estudados a influência da concentração de catalisador e do pH inicial do meio reacional. Foram realizados, também, ensaios de toxicidade com o organismo Lactuca sativa – sementes de alface, para avaliar a toxicidade da prednisolona pura, da mistura água e catalisador de BiOI e das alíquotas provenientes da reação de degradação da prednisolona após diferentes tempos. As amostras de Bi2WO6 apresentaram boa cristalinidade e semelhanças morfológicas apesar dos diferentes tratamentos. As amostras de BiOI, por sua vez, apresentaram diferenças significativas de morfologia, de microesferas para microplacas, quando foi feita a mudança de solvente e a amostra de BiVO4 apresentou um formato de paralelepípedo. Nos testes fotocatalíticos com a rodamina B, o catalisador que se mostrou mais ativo foi o BiOI cuja síntese continha PVP e etilenoglicol (kap = 0,0207 min-1) e o BiVO4 foi o que apresentou a menor atividade (kap = 0,0013 min-1). Na degradação da prednisolona, a maior taxa de degradação foi obtida com 1 g L-1 de catalisador e no pH natural do fármaco, 6,8. Os ensaios de toxicidade revelaram que nem a prednisolona nem a mistura água e catalisador são tóxicas para as sementes de alface, as alíquotas provenientes da reação, porém, tiveram um aumento de sua toxicidade com o aumento do tempo de reação. / In this work, solvo and hydrothermal methods were applied to synthesize three types of bismuth catalysts (Bi2WO6, BiOI and BiVO4) aiming to the apply it in heterogeneous photocatalysis under visible light. Were investigated the influences of reaction time, calcination, addition of poly (vinyl pyrrolidone) (PVP) and the solvent type during synthesis on their morphology, crystallinity, surface area and band gap. The catalysts were characterized by scanning electron microscopy (SEM), diffuse reflectance spectroscopy (DRS), X-ray powder diffraction (XRD) and nitrogen adsorption/desorption. To evaluate photocatalytic activity of the synthesized samples, experiments were carried out in a stirred batch reactor, with the catalyst in suspension and a LED lamp as a source of visible light. The test molecules chosen were the rhodamine B dye for determination of the samples with higher activity and subsequently the drug prednisolone, and then was studied the effect of catalyst concentration and initial pH of the reaction medium. Toxicity tests were also perfomed with organism Lactuca sativa – lettuce seeds, to the toxicity of pure prednisolone, water and BiOI catalyst mixture and aliquots from prednisolone degradation after different reaction times. As a result, the Bi2WO6 samples presented good crystallinity and morphological similarities despite having undergone different treatments. The BiOI catalysts presented a significant difference in morphology, microspheres to microplates, when changed the solvent, while the BiVO4 sample presented a parallelepiped shape. In the photocatalytic tests with rhodamine B, the catalyst with the highest activity was BiOI, containing PVP and ethylene glycol (kap = 0.0207 min-1) in its synthesis, and the BiVO4 was the catalyst with the lowest activity (kap = 0.0013 min-1). In the prednisolone degradation, the highest degradation rate was obtained with 1 g L-1 of catalyst and natural pH of the drug, 6.8. The toxicity tests showed that neither prednisolone nor water and catalyst mixture are toxic to lettuce seeds, aliquots from reaction, however, had an increase in their toxicity with increasing reaction time.

Thesis advisor: Matthias M. Waegele / Studying the visible light-driven photoredox catalysis coupled with transition-metal complexes is of overriding importance in the development of synthetic strategy. Comparing to conventional thermal catalysis, reactions catalyzed and/ or initiated by photon energy are not only attractive for establishing a more sustainable system, but also for their unique reactivity that has previously been inaccessible. However, one issue draws our attention is that such photoredox catalytic schemes often suffer from a limited substrate scope. To develop more efficient and effective synthetic strategies applicable to broader range of substrates, it is of our interest to construct an functional and reliable instrument to identify the critical mechanistic steps that lead to low product yield. To this end, we designed a time-resolved visible-pump/ infrared-probe spectroscopic measurement technique to monitor reaction dynamics in-situ. Using our transmission infrared setup, we effectively demonstrated in-situ photoexcitation and decay process of Tris(2,2′-bipyridyl)dichlororuthenium(II) hexahydrate in deuterated acetonitrile. In addition, to optimize signal resolution, an electronic filter was installed in one of the data-collecting channels to allow for concurrent AC-coupled and DC-coupled signal recording. A series of chopper wheel experiments was conducted to assure the functionality of the system and reliability of obtained data. / Thesis (MS) — Boston College, 2020. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.