Dissertations / Theses on the topic 'Spectrophotometric data'

El objetivo principal de esta tesis es el desarrollo de metodologías analíticas rápidas basadas en técnicas espectrofotométricas moleculares y análisis de datos multivariantes. Estas metodologías se han aplicado para la resolución de dos problemas analíticos relacionados con los aceites vegetales como materias primas.
Uno de ellos es la evaluación de las posibilidades que ofrecen los aceites vegetales como precursores de pre-polímeros. Se ha demostrado que la espectroscopía de infrarrojo combinada con tratamiento de datos de segundo orden es una herramienta útil para llevar a cabo el análisis cuantitativo de reacciones poliméricas modelo en las cuales intervienen aceites vegetales como reactivos iniciales.
El segundo es el control de calidad del biodiesel. Se han desarrollado dos métodos basados en análisis por inyección secuencial con detección UV-visible y tratamiento de datos de segundo orden para llevar a cabo la determinación de parámetros de interés para la caracterización del fuel.
L'objectiu principal d'aquesta tesi és el desenvolupament de metodologies analítiques ràpides basades en tècniques espectrofotomètriques moleculars i anàlisi de dades multivariants. Aquestes metodologies s'han aplicat a la resolució de dos problemes analítics relacionats amb els olis vegetals com a matèries primes.
Un d'ells és l'avaluació de les possibilitats que ofereixen aquests olis com a precursors de pre-polímers. S'ha demostrat que la espectroscopia d'infraroig combinada amb el tractament de dades de segon ordre és una eina útil per dur a terme l'anàlisi quantitatiu de reaccions polimèriques model en les quals intervenen olis vegetals com a reactius inicials.
El segon és el control de qualitat del biodiesel. S'han desenvolupat dos mètodes basats en l'anàlisi per injecció seqüencial amb detecció UV-visible i tractament de dades de segon ordre per dur a terme la determinació de paràmetres d'interès per a la caracterització del fuel.
The main objective of this thesis is the development of fast analytical methodologies based on molecular spectrophotometric techniques and multivariate data analysis. These methodologies have been applied to the resolution of two analytical problems related to the vegetable oils as raw materials.
One of them is the evaluation of the possibilities that modified vegetable oils offer as precursors of pre-polymers. It has been demonstrated that infrared spectroscopy combined with second-order data treatment is a powerful tool to carry out the quantitative analysis of model polymer reactions of interest to obtain vegetable oil-thermosetting materials.
The other one is the quality control of biodiesel. Two methods based on sequential injection analysis with UV-visible detection and second-order data treatment have been developed to determine the specific parameters of interest for the characterization of the fuel.

Les supernovae de type la (SNe la) sont un des piliers de la cosmologie observationnelle moderne, celles-ci étant de bonnes chandelles standards utilisables pour des mesures de distances dans l'univers. L'analyse cosmologique à partir des SNe la s'appuie sur les mesures d'objets à grands et petits décalages vers le rouge (z), et actuellement le faible nombre d'observations de ces derniers constitue une source majeure d'incertitude. Cette thèse s'inscrit dans le cadre de l'expérience SNfactory, qui a pour objectif l'observation de SNe la proches (0. 03 < z < 0. 08) grâce à un spectrographe de champ intégral, SNIFS. Le travail présenté a porté d'une part sur l'étalonnage de la voie photométrique de SNIFS, et d'autre part sur l'analyse des courbes de lumière spectrophotométriques issues des données de SNIFS. Ces études ont abouties à la création du premier diagramme d'Hubble spectrophotométrique pour des SNe la proches. Une chaîne d'extraction de rapports photométriques entre nuits, nécessaires pour l'étalonnage en flux des spectres, a été mise en oeuvre. Les erreurs systématiques de ces rapports ont été estimées comme étant inférieures à 2%, et les courbes de lumière spectrophotométriques d'étoiles standards montrent une précision de 5% pour l'étalonnage absolu en flux dans des conditions non-photométriques. Les résidus du diagramme d'Hubble obtenu présentent une dispersion plus petite que celui fait avec les données disponibles à ce jour. Un ajustement cosmologique sans K-correction montre une réduction supplémentaire de 5%, qui jusqu'à présent était indistinguable de la "dispersion intrinsèque" des SNe la
Type la supernovae (SNe la) are one of the pillars of modem observational cosmology, since they are good standard candies for distance measurements in the universe. The cosmological analysis using SNe la requires the observation of both high and low-redshift objects, and the smaller statistic of events on the latter case represents a major source of uncertainties. This thesis takes place within the SNfactory project, which aims to study nearby (0. 03 < z < 0. 08) SNe la using an integral field spectrograph, SNIFS. The presented work is divided into: a technical part, dealing with the acquisition, calibration and extraction of data from the SNIFS photometric camera; and an analysis where spectrophotometric light curves issued frc-m SNIFS spectra were obtained, and used to create the first spectrophotometric nearby Hubble diagram. An extraction pipeline of the differential photometric ratios between nights, needed for the flux calibration of the spectra, was built. The systematic errors affecting these ratios are estimated to be below 2%, and spectrophotometric light curves of standard stars show a 5% photometric precision of the full flux calibration on non-photometric conditions. The obtained nearby Hubble diagram presents a smaller residual scatter than the one made using currently available data. A K-correction free cosmological fit shows an additional reduction of 5% on the scatter, until now undistinguishable from the SNe la "intrinsic dispersion"

We present the initial results from a program aimed at establishing a network of hot DA white dwarfs to serve as spectrophotometric standards for present and future wide-field surveys. These stars span the equatorial zone and are faint enough to be conveniently observed throughout the year with large-aperture telescopes. The spectra of these white dwarfs are analyzed in order to generate a non-local-thermodynamic-equilibrium model atmosphere normalized to Hubble Space Telescope colors, including adjustments for wavelength-dependent interstellar extinction. Once established, this standard star network will serve ground-based observatories in both hemispheres as well as space-based instrumentation from the UV to the near IR. We demonstrate the effectiveness of this concept and show how two different approaches to the problem using somewhat different assumptions produce equivalent results. We discuss the lessons learned and the resulting corrective actions applied to our program.

The purpose of this study was to determine which type of bevel in a class IV dental composite restoration is the most esthetic and has the best blend to natural tooth structure via clinical and spectrophotometric evaluations. The null hypotheses were as follows: (1) there is no difference in visual evaluation rank scores among five groups of evaluators for each type of bevel; (2) there is no agreement in the visual evaluation rank scores of the seven groups of bevels among all evaluators or within each group of evaluators; (3) there is no difference in the lightness values among seven types of bevels at each of eight measurement points or for the whole tooth as measured by a spectrophotometer; and (4) there is no correlation between the visual evaluation and the spectrophotometric evaluation. The class IV samples were made via CAD/CAM milling for standardization. There were seven groups: negative control (no bevel); short (1mm) and straight bevel; short (1mm) and scalloped bevel; long (2mm) and straight bevel; long (2mm) and scalloped bevel; infinite (3+mm) and straight bevel; and infinite (3+mm) and scalloped bevel. The fractures were restored with the same type of dental composite via a digitally designed mold fabricated with a 3D printer. Once completed, the samples were randomized and evaluated visually by 91 people in five groups (faculty, graduate residents, pre-doctoral dental students, assistants/hygienists, and auxiliary staff). Evaluators placed the samples in the order they deemed least to most esthetic within a lightbox set to CIE Standard Illumination D65. After the visual evaluation, the lightness (L*) values were measured optically with a reflectance spectrophotometer at eight points on each of the seven bevel groups, as well as on an un-prepared typodont tooth used for reference. One-way ANOVA on ranked data with the post-hoc Bonferroni test was conducted to detect a significant difference in median rating score among five groups of evaluators, and Kendall’s W was used to evaluate an agreement among multiple raters. One-way ANOVA with the post-hoc Tukey’s HSD was used to find a significant difference in mean lightness values among seven types of bevels. Dunnett’s test was used to compare the reference group with each of the seven bevel groups when evaluating the lightness values. Pearson Correlation test along with the simple linear regression analysis were used to determine whether a significant relationship existed between visual evaluation scores and lightness values. The groups were ranked from least to most esthetic as follows: no bevel, short and straight bevel, short and scalloped bevel, long and straight bevel, long and scalloped bevel, infinite and straight bevel, and infinite and scalloped bevel by the 91 evaluators and Kendall’s W was 0.80 (strong agreement). Moreover, no significant difference in rating scores was found among the five groups of evaluators regarding each type of bevel (p>0.05). The overall mean lightness values observed in groups 1-3 were significantly higher than those in groups 6 and 7 (P< 0.05), but no significant difference was noted among groups 1-5 or among groups 4-7. As the lightness values measured by the spectrophotometer decreased, the overall visual evaluation score increased. The Pearson Correlation Coefficient of -0.89 indicated there was a strong negative correlation between the two variables (p=0.0066). Linear regression analysis revealed that the predictor of lightness was significant (strong negative correlation, R-square 0.99, p< 0.0001). The first null hypothesis was accepted and the second, third, and fourth were rejected. There was no difference in median visual evaluation rank scores among five groups of evaluators for each type of bevel, however, there was agreement in the ranked order as the findings of this study indicated that infinite and scalloped bevel was the most preferred and no bevel was the least preferred via a strong agreement the evaluators. There was a significant difference in lightness values among the seven bevel groups; the shorter bevels had higher L* values that were closer to the L* values of the reference tooth while the longer bevels had lower L* values. The correlation data showed that placing a longer bevel (3+mm) allowed for a more gradual transition and better blending capabilities between the tooth structure and dental composite. The overall conclusion from this study was the longer the bevel, the more gradual the change in Lightness (L*), which correlated to the more esthetic restoration, as determined by the evaluators.

Nickel silicate laterite deposits developed on ultra-mafic rocks are similar in many general respects but they vary considerably in detail. The mineralogy of these surficial deposits is very complex and difficult to determine because of the fine grained nature and solid solution characteristics of the hydrous secondary minerals and because many of the phases are actually mineraloids that are poorly ordered or amorphous. To try some new approaches toward clarification of these phases, 24 samples from New Caledonia and Puerto Rico ranging from the ophiolite-ultramafic olivine-pyroxene-chromite-serpentine substrate rocks upward through intermediate phases of weathering to the final oxide -hydroxide iron cap phase were analyzed with the infrared spectrophotometer (IR -10) and with the automated X –ray diffractometer. Four limonite samples were also mineralogically analyzed. Goethite, secondary quartz, cryptomelane, hematite, chromite, talc, thuringite, and garnierite have been identified in various samples as weathering profile products.

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Dissertacao (Mestrado)
IEA/D
Instituto de Quimica, Universidade de Sao Paulo - IQ/USP

Research Doctorate - Doctor of Philosophy (PhD)
This work presents a new development in the analysis of equilibrium investigations using spectrophotometric titrations to now allow the analysis of a number of titrations simultaneously. We describe this as the 'second order globalisation of the analysis'. The background of equilibrium analysis, particularly spectrophotometric analysis, leading up to second order global analysis is traced in Chapter 1. Spectrophotometric analysis was first used for very simple systems measured at one wavelength; this we have termed 'zeroth order analysis'. 'First order global analysis', the analysis of single titrations measured at many wavelengths, is the present standard of spectrophotometric analysis, proving more robust and useful for complex systems. Second order global analysis is shown here to allow the analysis of even more complicated equilibria and to overcome many of the difficulties found in first order global analysis. A computer program, EQUISPEC, was written to perform second order globalisation. The theory behind and characteristics of this program are described in Chapter 2 and its success on real equilibria is demonstrated in Chapter 3. It is shown to overcome the linear dependence of individual titrations (Zn²⁺-phen), to allow improved definition of minor species (Eu³⁺-phen, Eu³⁺-FNAC, and Eu³⁺-PDA), and to result in reduced uncertainties in the refined equilibrium constants (Cu²⁺-dien, Cu²⁺-N₃phenol, and nitr). Further 2^nd order global analysis proved invaluable in the investigation of the interaction of DTPA with In³⁺. This equilibrium was quantified in a series of competition experiments using HBED as an auxiliary coloured ligand. EQUISPEC can also perform first order global analysis in the usual way and this is done in Chapter 4 to examine the equilibria of SM³⁺ and DTPA versus a bifunctional DTPA analogue of relevance to nuclear medicine. It was also adapted and applied to the investigation of the high spin - low spin equilibrium for an Fe(III) complex. The instrumentation used for acquisition of the spectrophotometric data is described in Chapter 5. This Chapter also contains the description of some synthetic work, as well as the crystal structure of [Eu(FNAC)₂(TOPO)₂(NO₃)]. Fluroescence titrations are described and discussed in the context of seeking a greater understanding of the complexation of Eu³⁺ by ligands of relevance to fluroimmunoassay procedures.

Research Doctorate - Doctor of Philosophy (PhD)
This work presents the development and application of modern data acquisition and analysis techniques for the investigations of equilibrium and kinetic reactions. The analytical technique is known as second order global analysis and a background of this relatively novel approach has been given. The theory behind and characteristics of the computer programs developed analysis as part of this research are described in Chapter Two along with descriptions of the instrumentation and programs developed for the acquisition of both potentiometric and spectrophotometric data. Applications of the developed programs include a potentiometric and spectrophotometric study of the protonation and stability equilibria of a series of polydentate N-donor ligands, as detailed in Chapter Three. The combination of potentiometric and spectrophotometric analysis has been shown to be a powerful analytical tool. Spectrophotometric titrations were also combined with fast stop-flow experiments in order to elucidate the complex reaction mechanisms associated with helicating ligands. The helication of the ligand ‘PepdaH₂’ with copper(II) and nickel(II) is examined in Chapter Four, along with discussions concerning the ability to induce chirality in the helicates from the addition of a chiral counter ion. Investigations into chirality were further continued in Chapter Five where the stereoselectivity of a benzimidazole-based ligand was investigated with circular dichroism titrations. The synthesis and characterisation of the benzimidazole-based ligands are provided, including a study of the ability of the ligands to form higher order complexes as investigated using electrospray mass spectroscopy. Chapter Six provides an in-depth discussion concerning the use of combined glass hydrogen selective electrodes for the determination of equilibrium constants, as this was a major focus of this research. Different calibration techniques are discussed and a description of the internal calibration technique developed is provided along with examples of the advantages of performing internal calibration of the electrode.

Research Doctorate - Doctor of Philosophy (PhD)
This work presents the development and application of modern data acquisition and analysis techniques for the investigations of equilibrium and kinetic reactions. The analytical technique is known as second order global analysis and a background of this relatively novel approach has been given. The theory behind and characteristics of the computer programs developed analysis as part of this research are described in Chapter Two along with descriptions of the instrumentation and programs developed for the acquisition of both potentiometric and spectrophotometric data. Applications of the developed programs include a potentiometric and spectrophotometric study of the protonation and stability equilibria of a series of polydentate N-donor ligands, as detailed in Chapter Three. The combination of potentiometric and spectrophotometric analysis has been shown to be a powerful analytical tool. Spectrophotometric titrations were also combined with fast stop-flow experiments in order to elucidate the complex reaction mechanisms associated with helicating ligands. The helication of the ligand ‘PepdaH₂’ with copper(II) and nickel(II) is examined in Chapter Four, along with discussions concerning the ability to induce chirality in the helicates from the addition of a chiral counter ion. Investigations into chirality were further continued in Chapter Five where the stereoselectivity of a benzimidazole-based ligand was investigated with circular dichroism titrations. The synthesis and characterisation of the benzimidazole-based ligands are provided, including a study of the ability of the ligands to form higher order complexes as investigated using electrospray mass spectroscopy. Chapter Six provides an in-depth discussion concerning the use of combined glass hydrogen selective electrodes for the determination of equilibrium constants, as this was a major focus of this research. Different calibration techniques are discussed and a description of the internal calibration technique developed is provided along with examples of the advantages of performing internal calibration of the electrode.

Water quality monitoring is an essential element of the water quality management system and water treatment process. Conventional water quality monitoring relies on grab sampling and laboratory analysis, which is unable to provide quick responses to water quality events as it often takes hours and even days to transport and analyse water samples. Online water quality monitoring measures water quality continuously and allows quick responses to water quality events by providing real-time water quality data. In recent years, the online UV-Vis spectrophotometer has been reported as a promising technology for continuous water quality monitoring and process control. It reveals the real-time water quality changes and enables the development of surrogate parameters for online water quality monitoring and process control. However, there are some technic and data processing issues with using the online instruments for water quality monitoring. Besides, limited knowledge and research were reported on the utilisation of the online UV-Vis spectrophotometers for water quality management. This thesis project uses advanced data analytics to enhance the UV-Vis spectrophotometer for real-time water quality monitoring and treatment process control. Laboratory investigations were conducted to explore the impact of water matrix and suspended particles on the online water quality measurements using a submersible UV-Vis spectrophotometer, and to assess the water quality monitoring performance for different water sources. Both particle types and particle concentrations were found to have significant impacts on the UV254 measurements, showing that water quality data measured by the submersible UV-Vis spectrophotometer varied when the water matrix changes. These findings provide evidence that the particle influence on the UV-Vis measurements is source-water dependent. Surrogate models were developed as software techniques to eliminate particle impact from the measurements. Various software particle compensation techniques (surrogate models) including single wavelength compensation, linear regression compensation and multiplicative scatter correction methods were developed for online UV-Vis measurements of water quality. Moreover, cost-effective simple UV-Vis instruments could be employed in the field to monitor water quality instead of using sophisticated full-spectrum UV-Vis instruments. The real-time water quality measurement technology, UV-Vis spectrophotometer, was used for water treatment process control. Surrogate modelling approaches were used for the first to build coagulant dose determination models using only online UV-Vis spectra of raw water quality combined with chemometrics to determine coagulant doses and control the coagulation process for a drinking water treatment plant. The results revealed that an online UV-Vis spectrophotometer combined with a software surrogate model is a promising technology that determinates coagulant doses for real-time process control.
Thesis (Ph.D.) -- University of Adelaide, School of Chemical Engineering and Advanced Materials, 2022

Tesis (Doctor en Astronomía)--Universidad Nacional de Córdoba, Facultad de Matemática, Astronomía, Física y Computación, 2018.
Los núcleos activos de galaxias (AGN) se diferencian de las galaxias "normales" por el hecho de emitir una fracción significativa de energía que no puede ser explicada como resultado de procesos estelares. Esta fracción, proveniente de una región central muy compacta de la galaxia, es muy difícil de cuantificar. Los AGN del tipo "Narrow Line Seyfert 1" (NLS1) son una subclase de AGN con características de Seyfert 1 pero sin líneas anchas evidentes, lo cual implica grandes interrogantes sobre su estructura, dinámica y fuente central de excitación. A este tipo de galaxias se las define con el criterio de que el ancho a mitad de altura (FWHM) de la componente ancha de Hβ sea menor que 2000 km s-1 y que el cociente [OIII]λ5007/Hβ sea menor que 3. El estudio de los NLS1 puede brindarnos importante información sobre la evolución de los AGN y los mecanismos de ionización dominantes en las regiones más internas de estos objetos. Para estudiar estos objetos, seleccionamos una muestra de espectros a z < 0,1 obtenidos a partir del Sloan Digital Sky Survey. Utilizando la técnica de la síntesis espectral, separamos las diferentes componentes que contribuyen al espectro observado, a saber la componente estelar y no-estelar, y también la emisión del gas ionizado. En este trabajo se pretende cuantificar la contribución del núcleo activo al total del flujo observado y determinar el índice espectral más representativo en la región óptica del espectro en las galaxias NLS1. A partir de la técnica de síntesis espectral, también obtuvimos información sobre las diferentes poblaciones estelares presentes en estas galaxias. Por medio del espectro de emisión del gas, se determinó la dinámica y luminosidad de diferentes líneas de emisión, con las cuales estimamos masas de agujeros negros y tasas de acreción. Por último, se presenta un estudio detallado de la dinámica del gas y en particular de los vientos en la región central de la galaxia SDSS J093643.13+505249.6. Para ello se realizaron observaciones utilizando el Gemini Multi-Object Spectrographs con el Integral Field Unit (GMOS – IFU) en la región de Hβ + [OIII]λ5007 del espectro. De esta manera, obtuvimos mapas de flujo y de velocidades de estas líneas de emisión, con los cuales estimamos la extensión de los vientos en la región central de esta galaxia.
Active galactic nuclei (AGN) differ from "normal" galaxies in that they emit a significant fraction of energy that cannot be explained as the result of stellar processes. This fraction, coming from a very compact central region of the galaxy, is very difficult to quantify. Narrow Line Seyfert 1 (NLS1) AGNs are a subclass of AGNs with Seyfert 1 characteristics but without obvious broad lines, which implies big questions about their structure, dynamics and central source of excitation. These types of galaxies are defined by the criterion that the width at half maximum (FWHM) of the broad Hβ component is less than 2000 km s-1 and that the [OIII]λ5007/Hβ ratio is less than 3. The study of NLS1s can provide us with important information about the evolution of AGNs and the dominant ionization mechanisms in the innermost regions of these objects. To study these objects, we selected a sample of spectra at z < 0.1 obtained from the Sloan Digital Sky Survey. Using the spectral synthesis technique, we separate the different components contributing to the observed spectrum, namely the stellar and non-stellar component, and also the emission from ionized gas. In this work we aim to quantify the contribution of the active nucleus to the total observed flux and to determine the most representative spectral index in the optical region of the spectrum in NLS1 galaxies. From the spectral synthesis technique, we also obtained information about the different stellar populations present in these galaxies. By means of the gas emission spectra, we determined the dynamics and luminosity of different emission lines, with which we estimate black hole masses and accretion rates. Finally, a detailed study of the gas dynamics and in particular of the winds in the central region of the galaxy SDSS J093643.13+505249.6 is presented. For this purpose, observations were made using the Gemini Multi-Object Spectrographs with the Integral Field Unit (GMOS - IFU) in the Hβ + [OIII]λ5007 region of the spectrum. In this way, we obtained flux and velocity maps of these emission lines, with which we estimated the extent of the winds in the central region of this galaxy.
publishedVersion
Fil: Oio, Gabriel Andrés. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía, Física y Computación; Argentina.