Semiconductor diode lasers are successful tools in atomic spectroscopy. They are routinely used in frequency conversion applications to develop devices that access regions of the spectrum not directly available. This thesis describes the practical application of novel violet diode laser systems and their possible inclusion in spectroscopic systems. The design, assembly and successful operation of a doubly resonant optical parametric oscillator is described. There is discussion of the spectral behaviour of the device and the potential for pumping with a violet diode laser. Methods to adapt the output from the solitary diode devices are demonstrated with the use of microlensed diode lasers and extended cavity configurations. Details of the current tuning, linewidth and smooth tuning characteristics of a number of the lasers used are given. A commercial violet diode laser is used within an extended cavity to measure the hyperfine structure of atomic indium from a hollow cathode galvatron source at room temperature. Stabilisation of the diode laser to a line from the indium spectrum is attempted. The remainder of the thesis is concerned with the development of techniques to deliver clearer and more precise spectral information about trace species. Microlensed red and violet diode lasers are used to generate light at 254nm via sum frequency generation for the direct detection and modulation spectroscopy of mercury vapour, with microlensed lasers with modulation allowing more accurate discrimination between spectral features than direct absorption measurements. In addition Raman tweezers modulation spectroscopy is undertaken to investigate polymer microspheres and biological cell samples where the use of the modulation technique demonstrated improvements in the acquisition time and clarity of spectra through increased signal to noise and rejection of background fluorescence effects. A comparison between the direct and modulation techniques for all the systems indicates the greater sensitivity of the modulation technique.

A unique K-band selected high-redshift spectroscopic dataset (UDSz) is exploited to gain further understanding of galaxy evolution at z > 1. Acquired as part of an ESO Large Programme, this thesis presents the reduction and analysis of a sample of ∼ 450 deep optical spectra of a random 1 in 6 sample of the KAB < 23, z > 1 galaxy population. Based on the final reduced dataset, spectrophotometric modelling of the optical spectra and multi-wavelength photometry available for each galaxy is performed using a combination of single and dual component stellar population models. The stellarmass and age estimates provided by the spectrophotometric modelling are exploited throughout the rest of the thesis to investigate the evolution of massive galaxies at z > 1. Focusing on a K-band bright (K < 21.5) sub-sample in the redshift range 1.3 < z < 1.5 the galaxy size-mass relation has been studied in detailed. In agreement with some previous studies it is found that massive, old, early-type galaxies (ETGs) have characteristic radii a factor ~- 1.5 − 3.0 smaller than their local counterparts at a given stellar-mass. Due to the potential errors in spectrophotometric estimates of the stellarmasses at high redshift velocity dispersion measurements are derived for a sub-sample of massive ETGs at z > 1.3 in order to calculate dynamical mass estimates. To date, only a handful of objects at z > 1.3 have individual velocity dispersion estimates in the literature. Here the largest single sample (13 objects) of velocity dispersion measurements at high redshift is presented. The results for the sub-sample of objects with dynamical mass estimates confirm the results based on stellar mass estimates that high redshift massive systems are more compact than their local counterparts. The fraction of K-band bright objects at high redshift that are passively evolving is calculated with specific star-formation rates from the UV rest-frame continuum, [OII] emission and 24μm data. It is concluded that ∼ 58 ± 10% of the K < 21.5, 1.3 < z < 1.5 galaxy population is passively evolving. Various photometric techniques for separating star-forming and passively evolving galaxies are assessed by exploiting the accurate spectral types derived for the UDSz spectroscopic sample. Popular highredshift selection techniques are shown to fail to effectively select complete samples of passive objects with low levels of contamination. Using detailed information available for the UDSz dataset, various techniques are optimised and then used to estimate the passive fraction from the full UDS photometric catalog. The passive fraction results from the full photometric catalog are found to agree well with the results derived from the UDSz sample. With the Visible and Infrared Survey Telescope for Astronomy (VISTA) now starting to produce data, the opportunity has been taken to develop high-redshift galaxy population dividers based on the VISTA filters. Using the first data release from the VISTA Deep Extragalactic Observations (VIDEO) survey (VVDS D1 field), the passive fractions of K-band limited samples have been estimated to compare with results derived in the UDS. Within the errors the passive fraction estimates in the UDS and VISTA VVDS D1 field are found to agree reasonably well. Finally, composite spectra are used to study the evolution of various different galaxy sub-samples as a function of redshift, age, stellar-mass and specific star-formation rate. This work produces an remarkably clean result, showing that the massive, absolute Kband bright, passively evolving ETGs are always the oldest population, with ages close to the age of the Universe at z ∼ 1.4. In contrast, the late-type, low-mass, star-forming galaxies are always found to be much younger systems. This result strongly supports the downsizing scenario, in which more massive systems complete their stellar-mass assembly before lower-mass counterparts.

The nature of the thermal structure of hot Jupiter atmospheres is one of the key questions raised by the characterization of transiting exoplanets over the past decade. There have been claims that many hot Jupiters exhibit atmospheric thermal inversions. However, these claims have been based on broadband photometry rather than the unambiguous identification of emission features with spectroscopy, and the chemical species that could cause the thermal inversions by absorbing stellar irradiation at high altitudes have not been identified despite extensive theoretical and observational effort. Here we present high-precision Hubble Space Telescope WFC3 observations of the dayside thermal emission spectrum of the hot Jupiter HD 209458b, which was the first exoplanet suggested to have a thermal inversion. In contrast to previous results for this planet, our observations detect water in absorption at 6.2 sigma confidence. When combined with Spitzer photometry, the data are indicative of a monotonically decreasing temperature with pressure over the range of 1-0.001 bars at 7.7 sigma confidence. We test the robustness of our results by exploring a variety of model assumptions, including the temperature profile parameterization, presence of a cloud, and choice of Spitzer data reduction. We also introduce a new analysis method to determine the elemental abundances from the spectrally retrieved mixing ratios with thermochemical self-consistency and find plausible abundances consistent with solar metallicity (0.06-10 x solar) and carbon-to oxygen ratios less than unity. This work suggests that high-precision spectrophotometric results are required to robustly infer thermal structures and compositions of extrasolar planet atmospheres and to perform comparative exoplanetology.

Accurate knowledge of stellar parameters such as mass, radius, effective temperature, and composition inform our understanding of stellar evolution and constrain theoretical models. Binaries and, in particular, eclipsing binaries make it possible to measure directly these parameters without reliance on models or scaling relations. In this dissertation we derive fundamental parameters of stars in close binary systems with and without (detected) tertiary companions to test and inform theories of stellar and binary evolution. A subsample of 41 detached and semi-detached short-period eclipsing binaries observed by NASA’s Kepler mission and analyzed for eclipse timing variations form the basis of our sample. Radial velocities and spectroscopic orbits for these systems are derived from moderate resolution optical spectra and used to determine individual masses for 34 double-lined spectroscopic binaries, five of which have detected tertiaries. The resulting mass ratio M2/M1 distribution is bimodal, dominated by binaries with like-mass pairs and semi-detached classical Algol systems that have undergone mass transfer. A more detailed analysis of KIC 5738698, a detached binary consisting of two F-type main sequence stars with an orbital period of 4.8 days, uses the derived radial velocities to reconstruct the primary and secondary component spectra via Doppler tomography and derive atmospheric parameters for both stars. These parameters are then combined with Kepler photometry to obtain accurate masses and radii through light curve and radial velocity fitting with the binary modeling software ELC. A similar analysis is performed for KOI-81, a rapidly-rotating B-type star orbited by a low-mass white dwarf, using UV spectroscopy to identify the hot companion and determine masses and temperatures of both components. Well defined stellar parameters for KOI-81 and the other close binary systems examined in this dissertation enable detailed analyses of the physical attributes of systems in different evolutionary stages, providing important constraints for the formation and evolution of close binary systems.

Time-series spectropolarimetric observations of polar WX LMi and asynchronous polar BY Cam are presented. Magnetic field properties, radial velocities and optical polarization are investigated via consecutive observations with good phase sampling during a single orbital cycle. Both systems are found to have a decentred dipole magnetic field configuration. One of the poles of WX LMi has a field strength of 49 MG, while the other pole may have possible field strengths of 69, 104 or 207 MG, depending on the harmonic numbers of the cyclotron humps observed in the circularly polarized spectrum. For BY Cam, a field strength of 168 MG is found for one of the poles, while field strengths of 70, 160 or 212 MG are possible for the other pole.

Multi-sensitive microgel particles are covalently crosslinked polymeric chains with a colloidal dimension that can rapidly change their volume through various external stimuli such as pH, ionic strength, temperature, and magnetic and electric field. Due to these characteristics, increasing attention has been focus on the development of multi-sensitive microgels, mainly for application as drug delivery carriers. This study aimed to synthesise pH- and temperature-sensitive microgel particles, based on precipitation polymerisation of N-isopropylacrylamide and acrylic acid, with a defined size, narrow size distribution, spherical morphology and colloidal stability to be used as an oral drug carrier. In order to provide better biocompatibility and biodegradability in the synthesised material, some assays were performed, adding the chitosan biopolymer during the polymerisation of the monomers previously mentioned. This thesis also intended to contribute to a better understanding of the relationship between the microgel synthesis and their properties using spectroscopic techniques to monitor the microgel formation. A new approach was proposed to monitoring the process variables, monomer conversion and average particle size of the microgel particles, during precipitation polymerisation using NIR and UV-VIS-NIR high-resolution spectrophotometers coupled with a probe. Besides, the influence of reaction conditions in the physicochemical characteristics of microgel particles was extensively investigated as well as their potential as an oral drug carrier for insulin. The monitoring results pointed out the enormous potential of these spectroscopy techniques to monitor the precipitation polymerisation process, allowing control over the polymerisation reaction with quickly and directly acquisition of data in real-time. In general, pH- and temperature-sensitive microgels were successfully synthesised, and many formulations showed to be suitable for application as oral drug carriers. However, the preliminary in vitro release results were not satisfactory, and a more in-depth study between the interaction of the drug with the particles as well as the method of release is recommended. In conclusion, with a proper understanding of the influence of the process conditions (e.g., reagent concentrations) on the physicochemical properties of the microgels, it is possible to tailor the multi-sensitive microgels for the desired application. / Microgéis multisensíveis são partículas poliméricas covalentemente reticuladas, com uma dimensão coloidal, e com capacidade para mudar o seu volume através de vários estímulos externos, como por exemplo, pH, força iônica, temperatura e campos magnéticos ou elétricos. Devido a essas características, estas partículas têm recebido grande atenção, principalmente na aplicação como carreadores de fármacos. O objetivo deste estudo foi sintetizar partículas de microgéis sensíveis ao pH e à temperatura através da polimerização por precipitação dos monômeros N-isoproprilacrilamida e ácido acrílico, que tivessem tamanho definido, distribuição de tamanho estreita, morfologia esférica e estabilidade coloidal, para serem utilizadas como carreadores oral de fármacos. Com o intuito de proporcionar melhor biocompatibilidade e biodegradabilidade no material sintetizado, foram realizados alguns ensaios acrescentando o biopolímero quitosana durante a polimerização dos monômeros citados anteriormente. O presente trabalho também teve como objetivo contribuir para uma melhor compreensão da relação entre a síntese de microgéis e suas propriedades utilizando técnicas espectroscópicas para monitorar a formação dos microgéis. Uma nova abordagem foi proposta para monitorar as variáveis de processo, conversão de monômero e tamanho médio das partículas de microgel, durante a polimerização por precipitação através de espectrofotômetros NIR e UV-VIS-NIR acoplados a uma sonda. Além disso, a influência das condições da reação nas características físico-químicas das partículas de microgel foi extensivamente investigada, bem como o seu potencial como carreador oral de insulina. Os resultados do monitoramento indicaram o enorme potencial das técnicas espectroscópicas utilizadas, permitindo o controle da polimerização com aquisição rápida e direta dos dados em tempo real. Em geral, os microgéis sensíveis ao pH e à temperatura foram sintetizados com sucesso, e algumas formulações mostraram-se adequadas para aplicação como veículos de fármaco através da via oral. No entanto, os resultados preliminares da liberação in vitro não foram satisfatórios, e um estudo mais aprofundado entre a interação do fármaco com as partículas e o método de liberação é recomendado. Em conclusão, com uma compreensão adequada da influência das condições do processo (nesse caso, da concentração dos reagentes) nas propriedades físico-químicas dos microgéis, é possível ajustá-las para obtenção de microgéis multissensíveis com características adequadas para a aplicação desejada.

Monitoring of emulsion properties is important in many applications, like in foods and pharmaceutical products, or in emulsion polymerization processes, since aged and broken emulsions perform worse and may affect product quality. In machining processes, special types of emulsions called metalworking fluids (MWF) are widely used, because of its combined characteristics of cooling and lubrication, increasing the productivity, enabling the use of higher cutting speeds, decreasing the amount of power consumed and increasing tool life. Even though emulsion quality monitoring is a key issue in manufacturing processes, traditional methods are far from accurate and generally fail in providing the tools for determining the optimal useful life of these emulsions, with high impact in costs. The present study is dedicated to the application of a spectroscopic sensor to monitor MWF emulsion destabilization, which is related to changes in its droplet size distribution. Rapeseed oil emulsions, artificially aged MWF and MWF in machining application were evaluated, using optical measurements and multivariate calibration by neural networks, for developing a new method for emulsion destabilization monitoring. The technique has shown good accuracy in rebuilding the droplet size distribution of emulsions for monomodal and bimodal distributions and different proportions of each droplet population, from the spectroscopic measurements, indicating the viability of this method for monitoring such emulsions. This study is part of a joint project between the University of São Paulo and the University of Bremen, within the BRAGECRIM program (Brazilian German Cooperative Research Initiative in Manufacturing) and is financially supported by FAPESP, CAPES, FINEP and CNPq (Brazil), and DFG (Germany). / Sem resumo em português.

Peptídeos antimicrobianos são vistos como alternativas promissoras a serem empregadas pela iindústria farmacêutica no controle de infecções causadas por microrganismos, como também na indústria alimentícia, onde podem desempenhar papéis como conservantes naturais de alimentos. Plantaricina149 é um membro deste grupo, sendo composto por 22 resíduos de aminoácidos, com natureza catiônica e atividade inibitória sobre algumas bactérias patogênicas. Neste trabalho, foram sintetizados diferentes peptídeos análogos à Plantaricina149 para investigar suas ações sobre microrganismos (bactérias e fungos), a fim de correlacionar estes estudos com a ação lítica do peptídeo em modelos de membrana diversos (monocamadas e vesículas fosfolipídicas). A interação de Plantaricina149 com estes sistemas foi monitorada pelas espectroscopias de dicroísmo circular e fluorescência, ensaios de tensão superficial, calorimetria e ressonância plasmônica de superfície, e mostrou ser altamente específica para superfícies fosfolipídicas que apresentam densidade de cargas negativas, tais como a membrana celular de bactérias. A interação eletrostática inicial que se estabelece entre o peptídeo e os fosfolipídios é de extrema importância, sendo capaz de induzir uma estruturação helicoidal na região C-terminal do peptídeo, enquanto a região Nterminal contribui com as interações hidrofóbicas necessárias para a penetração do peptídeo nas camadas fosfolipídicas levando a ruptura das mesmas. De forma semelhante, a atividade antimicrobiana de Plantaricina149a (e alguns de seus análogos) também mostrou ser resultado das interações das duas regiões da molécula, e foi afetada com a retirada ou modificação da região N-terminal do peptídeo. Com a deleção desta região, o peptídeo passou a ter somente ação bacteriostática sobre Staphylococcus aureus e Pseudomonas aeruginosa, perdendo a capacidade bactericida. / Antimicrobial peptides are seen as promising alternatives to be employed in pharmaceutical industry for controlling infections caused by microorganisms, and also in food industry, where they can play roles as natural food preservatives. Plantaricina149 is a member of this group, constituted of 22 amino acid residues, cationic in nature and presenting inhibitory activity against some pathogenic bacteria. In this work, different Plantaricina149 analog peptides were synthesized to investigate their action against microorganisms (bacteria and fungi), with the aim of correlating these studies with the lytic action of the peptide on several membrane models (phospholipid monolayers and vesicles). The Plantaricina149 interaction with these systems was monitored by circular dichroism and fluorescence spectroscopies, surface tension assays, calorimetry and surface plasmon resonance, and showed to be highly specific to phospholipid surfaces that present negative charge density, such as the bacteria cell membrane. The initial peptide-phospholipids electrostatic interaction is extremely important, and it is capable of inducing a helical structure in the peptide C-terminal region, while the Nterminal region contributes with the hydrophobic interactions needed to the peptide penetration in the phospholipid layers and to the disruption of them. Similarly, the Plantaricina149 antimicrobial activity has also proved to be a result of the interactions from the two regions of the molecule, and it was strongly affected by the removal or modification of the peptide N-terminal region. Promoting the deletion of this region has left the peptide only with a bacteriostatic action against Staphylococcus aureus and Pseudomonas aeruginosa, removing its bactericide ability.

Neste trabalho são apresentados vários estudos com o peptídeo melanotrópico catiônico alfa-MSH (hormônio estimulador de melanócito) e análogos biologicamente mais ativos. Foram utilizadas as técnicas de fluorescência estática e resolvida no tempo, e RPE (ressonância paramagnética eletrônica). Com fluorescência, foi monitorado o aminoácido Trp (triptofano), presente em todos os peptídeos, e o aminoácido D-Nal (D-naphtul alanine), presente nos análogos cíclicos aqui estudados, para a obtenção de informações estruturais. Com RPE, utilizou-se marcadores de spin incorporados a dispersões lipídicas aniônicas de DMPG (1,2-dimyristoyl-sn-glycero-3-phospho-rac-glycerol), para o estudo da estrutura dos agregados anfifílicos e da interação peptídeo/lipídio, e o aminoácido paramagnético Toac (2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid), ligado covalentemente ao alfaMSH e a seu análogo linear MSH-I (Nle POT.4, DPhe POT.7-alfa-MSH), para o estudo comparativo da conformação destes peptídeos. Com marcadores de spin, foi feito um estudo sobre modificações que o alfa-MSH causa em vesículas de DMPG, correlacionando o aumento da concentração de moléculas de água, em toda a extensão da cadeia hidrocarbônica, com a diminuição da fluidez da bicamada lipídica. O perfil de polaridade da bicamada lipídica, medido em amostras congeladas, foi encontrado ser diferente do observado em lipídeos na fase fluida, particularmente na presença de moléculas polares. É mostrado aqui que fosfolipídeos paramagnéticos, marcados no 16o. carbono da cadeia acila, incorporados em vesículas, monitoram a presença de duas populações, na chamada fase intermediária do DMPG (entre a fase gel e a líquido-cristal). A presença das duas populações fica evidente com a comparação dos espectros de RPE obtidos na presença e ausência de alfa-MSH: o peptídeo parece fazer desaparecer um dos ambientes monitorados pelo marcador de spin. ) As estruturas de análogos cíclicos do alfa-MSH, contendo, além do Trp, o fluoróforo D-Nal, foram estudadas em solução aquosa e em presença de vesículas de DMPG, e comparadas com a do peptídeo natural. Medidas de fluorescência do Trp indicam que, em meio aquoso, a estrutura dos análogos cíclicos (na região do Trp) está próxima da conformação adquirida pelo alfa-MSH em bicamadas lipídicas, sugerindo que os peptídeos cíclicos encontram-se, em solução, em uma forma mais adequada para penetração na membrana. Comparando com resultados obtidos com alfa-MSH, nos peptídeos cíclicos, o Trp parece penetrar mais profundamente na membrana lipídica. O aminoácido D-Nal penetra na bicamada lipídica, tendo seu espectro de fluorescência, e tempo de vida do estado excitado, drasticamente alterados pela presença de vesículas de DMPG. Tanto por RPE do Toac, como através da fluorescência do Trp, observa-se dependência da conformação do alfa-MSH e MSH-I com o pH do meio, o que é atribuído a titulação de cadeias laterais dos peptídeos. A análise das curvas de titulação dos peptídeos alfa-MSH e MSH-I, por fluorescência do Trp, sugere pequenas diferenças conformacionais entre estes dois peptídeos em meio aquoso, sendo maior o efeito observado em pH alcalino. Mostra também que as estruturas dos análogos marcados com a sonda paramagnética, em solução aquosa, são ligeiramente diferentes daquelas dos peptídeos originais, apesar de ter sido observado que a inserção do Toac em peptídeos melanotrópicos não altera a atividade biológica dos mesmos / Some studies with the cationic melanotropic peptide a-MSH (a-melanocyte stimulating hormone), and analogues biologically more active are presented here. Steady-state and time resolved fluorescence and EPR (electron paramagnetic resonance) have been used. Peptide structural information was obtained by the fluorescence spectroscopy of both the amino acid Trp (tryptophan), present in all the peptides monitored here, and that of D-Nal (D-naphtyl alanine), present only in cyclic analogues. EPR of spin labels incorporated in anionic lipid dispersions of DMPG (1,2-dimyristoyl-sn-glycero-3-phospho-rac-glycerol) has been used to study amphiphilic aggregate structure and peptide/lipid interaction. EPR was also applied to a comparative structural study of the paramagnetic amino acid Toac (2,2 ,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid), covalently bound to a-MSH and its linear analogue MSH-1 (Nle4, DPhe7-a-MSH). With spin labels incorporated into the bilayers, it is shown that there is a correlation between the packing of fluid DMPG membranes, caused by a-MSH/lipid interaction, and the increase in bilayer interchain hydration. In frozen samples, alterations on the lipid bilayer polarity profile are shown to be different from those obtained at room temperature, particularly in the presence of polar molecules. It is shown here that paramagnetic phospholipids labeled at the 16th carbon of the acylchain, incorporated in DMPG vesicles, monitor the presence of two distinct sites in the lipid bilayer intermediate phase (between the gel and liquid crystal phases) . The presence of the two different spin populations is evident comparing the EPR spectra obtained in the presence and absence of a-MSH, as the peptide seems to make disappear one of the microenvironments monitored by the spin label.

G-quadruplexes (G4s) are nucleic acid structures formed from π-stacked planar sets of four Hoogsteen hydrogen bonded guanine bases. G4s emerged as potential therapeutic targets based on their ability to modulate gene expression and inhibit the ability of telomerase to elongate chromosomal telomeres. Raman spectroscopy, polarized Raman spectroscopy, surface-enhanced Raman spectroscopy (SERS), and other optical spectroscopic techniques were used to characterize the G4s formed by four different DNA sequences: human telomeric (HT), thrombin-binding aptamer (TBA), nuclease hypersensitive element III1 region of the c- Myc gene promoter (Myc), and a single loop-isomer of Myc (MycL1). / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2015. / FAU Electronic Theses and Dissertations Collection