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No description available.

Over recent years, the application of assisted reproductive techniques in the treatment of infertility has increased exponentially, yet these methodologies still remain inherently inefficient. It has long been established that the single greatest obstacle to improving the success of these treatments is determining the quality of the oocytes used. However, currently the methods available for oocyte assessment are mainly qualitative, and suffer due to a lack of standardisation. As such, the efficiency of fertility treatments could benefit from the introduction of a rigorous quantitative measure of oocyte quality and maturation. The principal aim of this thesis was to determine the potential of Raman spectroscopy when applied to the field of oocyte biology. Consequently, this thesis addressed three main areas of investigation: I. the intra-oocyte biochemical variation; II. the biochemistry of oocyte maturation; and finally, III. the effect of environment on the mature oocyte in vivo and in vitro. I. To investigate the presence of intra-oocyte biochemical variation, oocytes from various stages of development were analysed using high resolution Raman mapping, in combination with univariate and multivariate analysis. Images revealed variation between the germinal vesicle and ooplasm in immature oocytes, as well as intra-ooplasmic variation in all oocytes. II. The spectral analysis of oocytes derived from pre-antral and in vitro cultured follicles revealed significant variation: It was found that Raman spectroscopy could successfully discriminate between immature and mature oocytes. III. Finally, the spectral analysis of oocytes derived from unstimulated and stimulated ovulation cycles, as well as those derived from in vitro follicle cultures, revealed that although biochemically similar, in vitro matured oocytes demonstrated reduced protein content. Furthermore, greater spectral variation was observed in superovulated oocytes, which was found to describe the corresponding morphological quality. In conclusion, this thesis has demonstrated the effective application of Raman spectroscopy to the study of fixed murine oocytes. Raman mapping experiments have demonstrated this technique for the visualisation of biochemical variation which exists within the oocyte. Furthermore, using Raman spectroscopy, the identification of the biochemical variation resulting from different maturation mechanisms has been achieved, as has the discrimination of immature and mature oocytes. These results indicate that Raman spectroscopy holds promise as a quantitative analysis method in the field of fertility treatment.

No description available.

No description available.

Thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy to the Faculty of Engineering and the Built Environment, School of Chemical and Metallurgical Engineering, University of the Witwatersrand, Johannesburg, 2017 / Three medium rank C coals and a discard coal from different coalfields within the Karoo Basin were investigated. In this study, physico-chemical properties, ash fusion tests, quantitative single particle -electron probe X-ray microanalysis (SPAEPXMA), petrography, X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), and micro-Raman spectroscopy (mRs) were used as analytical techniques of choice to investigate the heterogeneous nature of coals, including mineralogical structure, mode of occurrence, and association of mineral matter in coals. The aim of the work was to highlight the significance of understanding the heterogeneous nature of coals, and to develop comprehensive and reliable approaches of characterising coals, coal ashes, and predict the behaviour of coals in coal conversion processes. The FTIR technique identified a well ordered kaolinite of authigenetic origin, characterised by inner hydroxyl group with H2O vibration at 3618 cm-1 absorption bands as the major mineral. Smectite and muscovite were identified at peaks 797 cm-1 and 799 cm-1 respectively, with quartz confirmed by the υ (Si-O-Si) and δ (Si-O) bands. The SPA-EPXMA data, modelled using principal component analysis (PCA) and chemical boundary classification (CBC), identified a diverse range of minerals such as alunite, chlorite, fayalite, almandine, anatase, ilmenite, brushite, goyazite, gypsum, dolomite, calcite, sodalite, rhodochrocite, and halite in raw coal samples. The mRs technique showed that in addition to bassinite, other oxidation products that formed at low temperature included lepidocrite and coquimbite. The technique proved to be ideal for the characterisation of high temperature ashes. High spatial resolution of mRs confirmed the presence of mixtures of anatase, brookite, and rutile, hematite, nephaline, apatite, crednerite and apatite in high temperature ashes. The SPA-EPMXA and mRs technique probed minerals on a micro-scale and their application could be extended to prediction of slagging and fouling behaviour in coals. The multiple technique approach revealed the importance of using a combination of techniques to characterise coals, and provided useful information that can help understand and relate the mineralogical and elemental composition of coals. This knowledge could be useful in designing conversion processes, and necessary downstream manipulations. / XL2018

Neste trabalho foram estudados três complexos de transferência de carga formados por aminas aromáticas e SO2. As aminas escolhidas foram a N,N-dimetilanilina (DMA), N,N-dietilanilina (DEA) e N-metilanilina (NMA). A interação entre a espécie doadora (amina) e a espécie aceptora (SO2) está bem esclarecida na literatura e trata-se de um reação típica de ácido-base de Lewis, porém existem alguns aspectos inexplorados e sem registros na literatura. Um desses aspectos é o fato de que complexos formados entre as aminas aromáticas e o SO2 dão origem a soluções oleosas com coloração vermelha intensa. O máximo de absorção eletrônica (UV-VIS) desses compostos está na faixa de 350 nm, com uma cauda que se estende pela região do visível, responsável pela cor. Um fato curioso é que a cor desses complexos se altera com a variação da temperatura de forma reversível. Em baixas temperaturas o complexo torna-se amarelo pálido e em altas temperaturas, vermelho escuro muito intenso. Um dos principais objetivos deste trabalho foi reinvestigar a interação de transferência de carga entre aminas aromáticas e SO2 na tentativa de responder tal questão. Para tal, foram utilizadas técnicas espectroscópicas (Raman e Infravermelho), sobretudo a espectroscopia Raman ressonante, com o auxílio de cálculos teóricos baseados na teoria do funcional da densidade (DFT). Os espectros Raman ressonante mostraram a intensificação seletiva de uma banda em cerca de 1140 cm-1 tanto com a variação da radiação quanto com a variação de temperatura. O fato dessa banda ter sido intensificada preferencialmente em radiações de excitação na região do visível e em altas temperaturas, permitiu que fosse proposta a presença de um outro cromóforo em solução. Portanto, além do complexo já bem caracterizado com estequiometria 1:1, propôs-se a presença de um complexo com estequiometria 2:1, ou seja, duas aminas conectadas por uma molécula de SO2, formando um complexo de transferência de carga com maior deslocalização eletrônica. A comparação entre as diferentes aminas mostrou que a formação dessas espécies associadas depende de um delicado balanço entre basicidade, impedimento estérico e possibilidade de interações específicas como ligações de hidrogênio. / In this work three charge-transfer complexes formed by aromatic amines and SO2 were studied. The chosen amines were N,N-dimethylaniline (DMA), N,N-diethylaniline (DEA) e N-methylaniline (NMA). The interaction between the donor (amine) and acceptor (SO2) is well established in the literature and is classified like a typical Lewis acid-base reaction, however there are some unexplored aspects that are lacking in the literature. One of such aspects is the fact that the complexes formed between the aromatic amines and SO2 gives origin of an oily intense red color solution. The maximum of electronic absorption (UV-VIS) of these complexes is near to 350 nm, with a tail that extends along the visible region, which is responsible for the color. A curious fact is that the complex color changes with the temperature variation in a reversible manner. At low temperatures, the color complex becomes pale yellow and at high temperatures, it turns a very intense dark red solution. One of the main objectives of this work was to reinvestigate the charge-transfer interaction between aromatic amines and SO2 trying to answer this question. For this, it was utilized spectroscopic techniques (Raman and Infrared), especially resonance Raman spectroscopy, with the support of theoretical calculations based on the Density Functional Theory (DFT). The resonance Raman spectra showed the selective enhancement of a band nearly 1140 cm-1 with both, the changing of the exciting radiation and the temperature variation. The fact of this band was preferentially enhanced with visible exciting radiations and at higher temperatures, allowed the proposition of the presence of another chromophore in solution. Therefore, besides the already well characterized complex with 1:1 stoichiometry, it was proposed the presence of a complex possessing a 2:1 stoichiometry, i.e. with two amines connected by a SO2 molecule, forming a charge transfer complex with higher electronic delocalization. The comparison among the different amines showed that the formation of such associated species depends on a delicate balance between basicity, sterical hindrance and the possibility of specific interactions such as hydrogen bonding

Medidas eletroquímicas, incluindo cronoamperometria, voltametria cíclica, procedimentos eletroquímicos de envelhecimento de filmes superficiais, espectroscopia de absorção no infravermelho, espectroscopia Raman in situ e ex situ, incluindo o efeito SERS, foram empregados no estudo da redução eletroquímica de íons perclorato a cloreto sobre eletrodo de estanho. Solução de perclorato de sódio 0,5 mol L-1 foi utilizada como eletrólito. Observou-se que a concentração máxima de cloreto produzida em decorrência da redução de íons perclorato (5,0 x 10-5 mol L-1) ocorre na região de potenciais localizada no final da contribuição de corrente da dupla camada elétrica e início da região de desprendimento de hidrogênio. A concentração limite de cloreto é decorrente do estabelecimento de um equilíbrio entre os íons cloreto na solução e cloreto adsorvido que inativa os sítios na superfície, impedindo a continuidade do processo. Programas de perturbação de potencial visando a eletromodificação da superfície do estanho foram aplicados, com o objetivo de verificar a ocorrência de mudanças das propriedades eletrocatalíticas dessas superfícies. A influência das variáveis, velocidade da perturbação, tempo de duração e limites de potencial na cinética de redução de perclorato e na concentração máxima de cloreto foi estudada. Em todos os casos a concentração máxima de cloreto detectada na solução foi de 2,0 x 10-5 mol L-1, exceto no tratamento de ativação eletroquímica quando essa concentração atinge 5,0 x 10-5 mol L-1. A influência da presença de óxidos superficiais, temperatura e agitação da solução, pH, e tempo de polarização no processo de redução de perclorato também foi avaliada. Concluiu-se que (i) a presença de óxidos catalisa o processo de redução; (ii) a influência da temperatura é significativa a 70 °C; (iii) a agitação e o pH da solução não exercem influência na concentração máxima de cloreto produzida e (iv) a concentração máxima de cloreto estabiliza-se após cerca de 150 minutos de polarização. / Electrochemical measurements including chronoamperometry, cyclic voltammetry, film surface electrochemical ageing procedures, FTIR and Raman spectroscopy including the SERS effect were carried out in order to study the electrochemical reduction of perchlorate ions at tin electrodes. Sodium perchlorate solution 0.5 mol L-1 was employed as electrolyte. It was observed that maximum chloride concentration produced by the perchlorate reduction (5.0 x 10-5 mol L-1), takes place within a potential range comprising the negative side of de double layer region and the positive side of the hydrogen evolution region. The upper limit of chloride concentration occurs due to the establishment of an equilibrium between the chloride ions in solution and the adsorbed chloride ions that blocks the surface sites where the reduction process takes place. In order to electromodify the tin surface, the electrode was subjected to perturbing potential programs, aiming to evaluate changes in the electrocatalytic properties of the modified sufaces. The influence of the experimental variables perturbation sweep rate as well as perturbation time and potential limits on the perchrolate reduction kinetic and on the maximum chloride concentration was studied. Except to the activation treatment, the maximum chloride concentration was 2.0 x 10-5 mol L-1 for all the applied perturbation programs. The influence of the oxides on the electrode surface, stirring, temperature, pH and polarization time on the reduction process was evaluated too. It was shown that (i) the presence of oxides on the electrode surface favors the reduction reaction; (ii) there is significant influence of temperature at 70 °C; (iii) pH and stirring the solution exerts no influence on the maximum chloride concentration produced and (iv) the maximum chloride concentration produced by electroreduction is reached after 150 minutes.

En este proyecto se ha desarrollado un equipo de espectroscopía Raman, implementado completamente en el Laboratorio de Óptica de la Pontificia Universidad Católica del Perú. Aunque sus características de operación aún no son comparables con los equipos comerciales de alta precisión, considero que se han obtenido resultados importantes. Se ha detectado la señal Raman de muestras de referencia en los estados sólido (polvo) y líquido; este es el resultado de un minucioso trabajo en la etapa de optimización del equipo, para la cual se ha establecido un protocolo de acciones que facilitará la réplica de equipos de espectroscopia Raman cuyo rango espectral de trabajo depende de la densidad de la rejilla de difracción y la frecuencia del láser empleado. El equipo de espectroscopía Raman implementado en este proyecto opera en el visible y emplea como fuente de excitación un láser doblado de estado sólido de Nd: YVO4 que emite en 532 nm con una potencia de 25 mw. Como sistema de detección y procesamiento de la señal Raman se empleó el espectrómetro Ocean Optics USB 4000-UV-VIS-ES y su software Spectra Suite. El equipo Raman tiene una resolución óptica (FWHM) de 1.41 nm (38 cm-1) y un rango espectral de 220 a 4000 cm-1. La validación del equipo Raman se desarrolló por contrastación de resultados, comparando los espectros Raman de muestras de laboratorio con la información disponible en la literatura existente. Se evaluaron las muestras líquidas: alcohol etílico, alcohol metílico, alcohol butanol, alcohol propanol, alcohol 2-propanol y las muestras sólidas: óxido de titanio, oxido de zinc y azufre. / Tesis

Neste trabalho foram estudados três complexos de transferência de carga formados por aminas aromáticas e SO2. As aminas escolhidas foram a N,N-dimetilanilina (DMA), N,N-dietilanilina (DEA) e N-metilanilina (NMA). A interação entre a espécie doadora (amina) e a espécie aceptora (SO2) está bem esclarecida na literatura e trata-se de um reação típica de ácido-base de Lewis, porém existem alguns aspectos inexplorados e sem registros na literatura. Um desses aspectos é o fato de que complexos formados entre as aminas aromáticas e o SO2 dão origem a soluções oleosas com coloração vermelha intensa. O máximo de absorção eletrônica (UV-VIS) desses compostos está na faixa de 350 nm, com uma cauda que se estende pela região do visível, responsável pela cor. Um fato curioso é que a cor desses complexos se altera com a variação da temperatura de forma reversível. Em baixas temperaturas o complexo torna-se amarelo pálido e em altas temperaturas, vermelho escuro muito intenso. Um dos principais objetivos deste trabalho foi reinvestigar a interação de transferência de carga entre aminas aromáticas e SO2 na tentativa de responder tal questão. Para tal, foram utilizadas técnicas espectroscópicas (Raman e Infravermelho), sobretudo a espectroscopia Raman ressonante, com o auxílio de cálculos teóricos baseados na teoria do funcional da densidade (DFT). Os espectros Raman ressonante mostraram a intensificação seletiva de uma banda em cerca de 1140 cm-1 tanto com a variação da radiação quanto com a variação de temperatura. O fato dessa banda ter sido intensificada preferencialmente em radiações de excitação na região do visível e em altas temperaturas, permitiu que fosse proposta a presença de um outro cromóforo em solução. Portanto, além do complexo já bem caracterizado com estequiometria 1:1, propôs-se a presença de um complexo com estequiometria 2:1, ou seja, duas aminas conectadas por uma molécula de SO2, formando um complexo de transferência de carga com maior deslocalização eletrônica. A comparação entre as diferentes aminas mostrou que a formação dessas espécies associadas depende de um delicado balanço entre basicidade, impedimento estérico e possibilidade de interações específicas como ligações de hidrogênio. / In this work three charge-transfer complexes formed by aromatic amines and SO2 were studied. The chosen amines were N,N-dimethylaniline (DMA), N,N-diethylaniline (DEA) e N-methylaniline (NMA). The interaction between the donor (amine) and acceptor (SO2) is well established in the literature and is classified like a typical Lewis acid-base reaction, however there are some unexplored aspects that are lacking in the literature. One of such aspects is the fact that the complexes formed between the aromatic amines and SO2 gives origin of an oily intense red color solution. The maximum of electronic absorption (UV-VIS) of these complexes is near to 350 nm, with a tail that extends along the visible region, which is responsible for the color. A curious fact is that the complex color changes with the temperature variation in a reversible manner. At low temperatures, the color complex becomes pale yellow and at high temperatures, it turns a very intense dark red solution. One of the main objectives of this work was to reinvestigate the charge-transfer interaction between aromatic amines and SO2 trying to answer this question. For this, it was utilized spectroscopic techniques (Raman and Infrared), especially resonance Raman spectroscopy, with the support of theoretical calculations based on the Density Functional Theory (DFT). The resonance Raman spectra showed the selective enhancement of a band nearly 1140 cm-1 with both, the changing of the exciting radiation and the temperature variation. The fact of this band was preferentially enhanced with visible exciting radiations and at higher temperatures, allowed the proposition of the presence of another chromophore in solution. Therefore, besides the already well characterized complex with 1:1 stoichiometry, it was proposed the presence of a complex possessing a 2:1 stoichiometry, i.e. with two amines connected by a SO2 molecule, forming a charge transfer complex with higher electronic delocalization. The comparison among the different amines showed that the formation of such associated species depends on a delicate balance between basicity, sterical hindrance and the possibility of specific interactions such as hydrogen bonding