O Brasil destaca-se como um dos maiores produtores mundiais de mamão, fruto apreciado em todo o mundo pelo sabor e polpa delicada. Os compostos voláteis contribuem para a formação do aroma do fruto, o que faz deles essenciais para o desenvolvimento de características sensoriais que definem sua apreciação pelos consumidores. Os principais compostos de aroma do mamão incluem, principalmente, terpenos, ésteres, aldeídos, álcoois, ácidos orgânicos e cetonas, com destaque para o monoterpeno linalool que é o composto mais abundante na cultivar \'Golden\'. Embora a biossíntese de compostos voláteis seja particularmente afetada pelos tratamentos para consevação pós-colheita, estes são essenciais para a comercialização do mamão, em vista de sua alta perecibilidade. O uso de baixas temperaturas tem sido um dos métodos mais empregados para extensão de vida pós-colheita do mamão. Precedentes da literatura indicam que o tratamento pós-colheita com metil jasmonato (MJ) é capaz de reduzir possíveis efeitos prejudiciais decorrentes do armazenamento a baixa temperatura. Além disso, a aplicação do metil jasmonato em frutos é capaz de estimular a atividade de enzimas das vias de produção de compostos voláteis. Desta forma, o presente trabalho tem por objetivo avaliar os efeitos da aplicação pós-colheita do MJ em mamão (Carica papaya L. cv \'Golden\'), focando os efeitos sobre as vias de biossíntese de componentes voláteis do aroma, em frutos amadurecidos a temperatura de 22ºC, assim como em outros armazenados a 10ºC seguido de transferência a 22ºC para o pleno amadurecimento. Além dos perfis de compostos voláteis, também foram avaliados os perfis de respiração, produção de etileno, cor da casca, quantificação de MJ e expressão gênica de linalool sintase (LIS). Dada a importância do linalool para o aroma característico do mamão, as variações na transcrição de um gene da linalool sintase foram avaliadas buscando correlacioná-las aos efeitos dos tratamentos na produção dos compostos voláteis. O tratamento com MJ influenciou a produção de compostos voláteis, particularmente de linalool e hexanal nos grupos mantidos a 10ºC. Os frutos tratados com o hormônio apresentaram maior abundância do composto quando comparados ao grupo controle. Embora o protocolo de tratamento empregado não tenha conseguido recuperar os altos níveis encontrados nos frutos armazenados a 22ºC, não se exclui a possibilidade de que outros desenhos experimentais possam responder de maneira ainda mais satisfatória a este mesmo tratamento / Brazil stands out as one of the world\'s largest producers of papaya, fruit appreciated worldwide for it taste and delicate pulp. The volatile compounds contribute to the formation of the flavor of the fruit, making them essential for the development of sensory characteristics that define their appreciation by consumers. The main papaya flavor compounds include mainly terpenes, esters, aldehydes, alcohols, organic acids and ketones, especially the monoterpene linalool which is the most abundant compound in the cultivar \'Golden\'. Although the biosynthesis of volatile compounds is particularly affected by postharvest treatments for conservation, those are essential for the marketing of papaya, in view of their high perishability. The use of low temperatures has been one of the most used methods for extension of papaya postharvest life. Previous literature indicate that postharvest treatment with methyl jasmonate (MJ) is capable of reducing possible adverse effects arising from storage at low temperature. Furthermore, the application of methyl jasmonate in fruits is able to stimulate the activity of the enzymes of volatiles production pathways. Thus, this study aims to evaluate the effects of postharvest application of MJ in papaya (Carica papaya L. cv \'Golden\'), focusing on the effects in the biosynthetic pathways of volatile aroma compounds in fruit ripened to temperature of 22ºC, as well as other stored at 10ºC followed by transfer to 22ºC for the complete maturation. In addition to the volatile compounds profiles were also evaluated respiration profiles, ethylene production, peel color, quantification of MJ and gene expression of linalool synthase (LIS). Given the importance of linalool to the characteristic aroma papaya, changes in the transcription of a linalool synthase gene were evaluated seeking to correlate them to the treatment effects on the production of volatile compounds. Treatment with MJ influence the production of volatile compounds, particularly linalool and hexanal in the groups kept at 10ºC. Fruits treated with the hormone had higher abundance of the compound when compared to the control group. Although the treatment protocol employee has not been able to recover the high levels found in fruits stored at 22ºC, do not exclude the possibility that other experimental designs can respond even more satisfactorily to this same treatment.

Whilst biodiesel has many advantages as a renewable-energy fuel and as a substitute source of petroleum diesel, it suffers from poor performance at both low temperatures and high pressures. Not only does biodiesel crystallise at low temperatures below ~0 °C, but it also crystallises under the high pressures experienced in common-rail and injector systems within diesel engines. Crystalline solids induced by temperature and pressure can clog filters and injectors in the diesel engine, thereby causing engine failure. This thesis focuses on developing an enhanced understanding of the behaviour of biodiesel using a range of spectroscopy and diffraction techniques. The crystallisation behaviour of biodiesel at high pressure (0.1 GPa to 4 GPa) or low temperature (0 °C to -40 °C) was studied in this work. Structural phase transitions of the components of biodiesel induced by both temperature and pressure were observed. On account of the complex nature of biodiesel, it proved difficult to characterise these changes in biodiesel itself. Instead, one of the main components, methyl stearate, was therefore investigated. The crystallisation behaviour of methyl stearate is temperature-sensitive. A new polymorph of form II was successfully characterised by single crystal diffraction - by growing crystals from a saturated carbon disulfide solution at room temperature while data collection was conducted at 120 K. Form III was obtained by crystallisation from melt followed by slow cooling. Structural characterisation using single crystal diffraction showed disordered packing behaviour of the molecules in this form. The crystal structure of form IV was obtained using a combination of synchrotron X-ray powder diffraction and high resolution neutron powder diffraction. It was crystallised from the melt by quench cooling at low temperature. The thermal expansion behaviour of this form was also investigated in this work. Furthermore, a phase transition from form IV to form V was observed in neutron diffraction experiments for a fully deuterated sample, but no evidence for this transition was observed in X-ray diffraction studies. Due to the complexity of methyl stearate and the limitations of the experimental data, the crystal structure of form V was not solved. In addition to the temperature studies, the crystallisation behaviour of methyl stearate under variable pressure conditions was investigated in this work. A diamond-anvil cell was employed to generate high-pressure environments. Synchrotron high-pressure X-ray powder diffraction and Raman spectroscopy showed that pressures of as little as 0.1 GPa can induce form IV of methyl stearate to convert to form II. Four phase transitions in the pressure range of 0.1 GPa to 6.3 GPa were also observed. The phase behaviour of methyl stearate induced by pressure is reversible and form II was recovered when the pressure was released. The structure of these high-pressure phases of methyl stearate have still to be determined. High-pressure neutron powder diffraction experiments have also been conducted with form IV of methyl stearate using a Paris-Edinburgh Press. Fluorinert (FC-87) was employed as pressure-transmitting medium to generate hydrostatic condition. No evidence of a phase transition was observed in the pressure range up to 3.31 GPa.

Orientador: Keizo Yukimitu / Resumo: Com a crescente populacional a demanda pelos polímeros aumentou significativamente, levando assim a pesquisas cientificas visando adequar materiais as nossas necessidades. O PMMA ou acrílico é muito utilizado em nosso cotidiano, sendo um material muito versátil com aplicabilidade em diversos setores. O intuito deste trabalho foi realizar a produção de um filme de acrílico [Poli(metil-metacrilato)] isento de bolhas e transparente, a qual tivesse uma repetibilidade. Foi realizada a dopagem com terras raras, sendo o Óxido de Érbio e o Óxido de Itérbio escolhidos como dopantes em diferentes concentrações de gramas/mol por gramas/mol (0 % referência, 5 %, 10%, 15% e 20 %). Logo após foi feita a caracterização dos filmes, determinando o índice de refração das amostras utilizando o Interferomêtro de Michelson com laser He-Ne (vermelho) de comprimento de onda de 632,8 nm. Notamos que o índice de refração do PMMA na amostra de referência aumentou gradativamente com as dopagens, o laser diodo na cor verde de comprimento de onda de 532 nm também foi utilizado e os resultados demostraram comportamentos similares. A Espectroscopia no Infravermelho por Transformada de Fourier (FTIR) foi realizada, observando o aparecimento de picos característicos dos elementos dopantes nas amostras e que esses picos aumentavam conforme a concentração de dopagem aumentava. A Difração de Raios-X (DRX) nos mostrou a incidência picos de cristalinidade referentes aos elementos dopantes em contraste com o espec... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: With the growing population demand for polymers has increased significantly, leading to scientific research aimed at adapting materials to our needs. PMMA or acrylic is widely used in our daily lives, being a very versatile material with applicability in several sectors. The purpose of this work was to produce an acrylic film [Poly (methyl-methacrylate)] which had a repeatability. Rare earth doping was performed, with Erbium Oxide and Ytterbium Oxide chosen as dopants in different concentrations of grams / mole per gram / mole (0% reference, 5%, 10%, 15% and 20%). After the characterization of the films, determining the refractive index of the samples using the Michelson Interferometer with He-Ne (red) laser of wavelength of 632.8 nm, we noticed that the refractive index of the PMMA in the sample of reference period increased gradually with doping, the green diode laser wavelength of 532 nm was also used and the results demonstrated similar behaviors. Fourier Transform Infrared Spectroscopy (FTIR) was performed, observing the appearance of characteristic peaks of the dopant elements in the samples and that these peaks increased as the doping concentration increased. X-ray Diffraction (XRD) showed us the incidence of crystallinity peaks relative to the dopant elements in contrast to the normal PMMA spectrum demonstrating the insertion of the rare earths into the matrix structure. / Mestre

L'épigénétique est un composant essentiel du fonctionnement des génomes eucaryotes. Les divers phénomènes épigénétiques modifient l’état chromatinien et participent à la plasticité du génome, mais aussi au maintien de son identité fonctionnelle à travers les générations cellulaires. Parmi ces processus, la méthylation de l’ADN joue un rôle fondamental dans la régulation de l’expression des gènes.Chez les mammifères, la méthylation de l'ADN est associée à la répression transcriptionnelle, et elle remplit au moins trois fonctions essentielles. Premièrement, elle permet de réprimer les séquences répétées afin de préserver l’intégrité du génome. Deuxièmement, la méthylation contrôle l’expression des gènes soumis à l’empreinte parentale, qui sont des régulateurs cruciaux du développement et de la vie adulte. Enfin, la méthylation permet de réprimer certains gènes tissu-spécifiques dans les organes où ils doivent être silencieux. En plus de ces rôles physiologiques, la méthylation est liée au cancer. En effet, des patrons de méthylation anormaux sont fréquemment observés dans les cellules tumorales, et ces anomalies participent à la transformation cellulaire par plusieurs mécanismes.La méthylation exerce ces effets par l'intermédiaire de protéines dédiées, qui reconnaissent spécifiquement l'ADN méthylé et contrôlent la transcription en modulant la chromatine. Trois familles de protéines liant l'ADN méthylé sont connues chez les mammifères, et elles totalisent entre elles neuf membres. De nombreux arguments suggèrent que cette liste est encore incomplète, et que des protéines humaines liant l'ADN méthylé restent à découvrir. Dans cette optique, nous avons opté pour deux types d’approches distinctes, une approche basée sur la littérature et une approche génétique. L’étude des protéines candidates ne nous a pas permis d’identifier de nouvelles protéines liant l’ADN méthylé et l’approche génétique par phage display a révélé deux protéines intéressantes, CHD3 et HMGB1 qui doivent désormais être validées par des approches in vivo et in vitro.Par ailleurs, nous avons entrepris l’étude de la régulation des éléments répétés par la protéine Zbtb4 chez la souris. Les expériences préliminaires indiquent une possible régulation des satellites mineurs par Zbtb4. Le rôle de cette régulation sera, par la suite, approfondi. / Epigenetic phenomena are key contributors to the function of eukaryotic genomes. These processes act on chromatin, and they are used to render the genome dynamic, but also stable throughout successive rounds of cell division. Among epigenetic processes, DNA methylation is especially well known for its role in the regulation of gene expression.In mammals, DNA methylation is strongly correlated with transcriptional repression, and fulfills at least three essential roles. First, it maintains repeated sequences transcriptionally silenced, thus ensuring the stability of the genome. Second, it is responsible for the proper regulation of parentally imprinted genes, which are crucial regulators of embryonic development and adult life. Finally, DNA methylation ensures that some tissue-specific genes are kept inactive in the organs in which they should be repressed. Besides these roles in the physiology of normal cells, DNA methylation has strong links to cancer. Indeed the pattern of DNA methylation on the genome is frequently altered in cancer cells, and these anomalies contribute to transformation by several mechanisms.DNA methylation does not control transcription directly, but instead acts via a set of dedicated proteins that specifically recognize methylated DNA and repress transcription by acting at the chromatin level. At present, three families of such proteins, totalling 9 members altogether, are known in humans. However, several lines of evidence suggest that the list is not exhaustive, and that other human proteins that bind methylated DNA remain to be found. This was the goal of the current project.To this end, we opted for two distinct types approaches, an approach based on literature and a genetic approach. The study of candidate proteins does not allow us to identify new methylated DNA binding proteins and the genetic approach by phage display revealed two proteins of interest, HMGB1 and CHD3 that must now be validated by in vivo and in vitro approaches.Furthermore, we studied the regulation of DNA repeats by Zbtb4 in mice. Preliminary results show a regulation of minor satellites by Zbtb4. The role of this regulation will be analyse further in the future.

Titanium Dioxide is a naturally occurring oxide of titanium. It has a wide range of uses in commercial products for providing whiteness and opacity. It has photocatalytic properties and can also be used to produce electricity in its nanoparticles form. This research is focused on investigating the effect of titanium dioxide nanoparticles in analysis of compounds using luminescence-based techniques. Quenching, which is one of the basic problems of fluorescent measurements, was studied in the presence of molecular oxygen and methyl iodide. The rutile phase of titanium dioxide nanoparticles was synthesized by the acid hydrolysis of titanium isobutoxide at low temperatures with nitric acid. The crystalline powder was dissolved at different concentrations and used to monitor the fluorescence intensities of carbazole, pyrene, and fluoranthene in the presence of methyl iodide and oxygen. Quenching by molecular oxygen was studied by comparing the fluorescence intensities of compounds with and without degassing the solutions. Titanium Dioxide was found to exhibit interesting effects on the fluorescent intensities of these compounds in the presence of quenchers.

This dissertation is related to the understanding of catalytic reactions of metal oxides. For several decades, the surfaces and bulk of materials have been probed to determine additional properties that relate to photocatalytic applications. This investigation furthers these efforts by the (a) modification of a metal oxide surface to isolate known influences of chemical properties and (b) proposing and utilizing a novel methodology for attribution of photocatalytic activity to a discernable influence. For the first effort, by effectively utilizing a known technique for a new application on a metal oxide, such isolations can be made despite unfavorable states. For the second effort, a reduction in the influence of surface states for metal oxides is effectively performed, providing the isolation of influences originating from the bulk. The challenge with such a proposal is verifying such bulk states have been adequately isolated as external influences would obviously distort any conclusions. Thus, techniques to both create such bulk states and eliminate unwanted combinations thereof are additionally required and must be provided for. Lastly, a determination of the photocatalytic activity is made to these states and results are provided.

Immunologic competence is correlated with resistance to infectious disease which may be affected by exposure to certain compounds. Methyl parathion (MP) and carbofuran (CF) have been reported to affect the development of active immunity in the rabbit and the present research was conducted to quantify the dosage relationships of these two pesticides to both host resistance and acquired resistance in the mouse. Preliminary study was made on the virulence of Salmonella typhimurium in mice. Mortality rates among infected animals fed Purina Laboratory Chow diet providing 0.08, 0.7 3.0 mg MP/kg/day or 0.1, 0.6, 1.0 mg CF/kg/day along with untreated controls were determined and protection afforded the animals by vaccination under the influence of chemical treatment was examined. The nature of dose response was further investigated with the study of various parameters of host defense against microbial infection. Measurements were made of the bacterial population in tissues of mice during and after the course of infection, differential leukocyte counts, in vivo and in vitro opsonic effect of serum, clearance of the reticulo-endothelial system, agglutination titers of serum, total serum gamma-globulin levels, serum immunoglobulin levels with classes and subclasses, and lymphocyte response to mitogen stimulation. Dosage-related increases in mortality were seen in unvaccinated mice under both chemical treatments, and protection by immunization was decreased. Pesticide treatment extending beyond two weeks was required to obtain significant increases in mortality. Increased mortality was associated with increased numbers of viable bacteria in blood, decreased total gamma-globulins and specific immunoglobulins in serum, and reduced splenic blast transformation in response to mitogens. Serum opsonic activity of CF-treated animals was slightly reduced. These results support those of other investigations indicating effects of environmental toxicants upon the resistance and immune competency of experimental animals.

TiO2 photocatalysis is been widely studied for air and water purification applications; titanium dioxide is the most used semiconductor principally because its low cost, stability and chemical properties. However it only utilizes the UV portion of the solar spectrum as an energy source (less than 4% of the total sunlight energy). This behavior is due to its high band gap value of 3.2 eV. The modification of light harvesting properties of TiO2 by doping has become an important research topic to achieve an efficient operating range under UV and visible light. In addition, the structure and surface properties of photocatalysts play an important role. This thesis explores the effects of Zn doped TiO2, prepared by the sol-gel method, on its photocatalytic activity to decompose organics and the characterization of the doped samples. Since this study is part of a collaborative initiative, the samples were synthesized and provided by Dr. A. R. Phani from the Department of Physics, University of L'Aquila. Preliminary examination revealed a relatively low photocatalytic efficiency of the samples. The objective is to modify/improve its properties by high energy ball milling which is expected to generate accumulations of defects, particle size reduction and an increase in the active surface area. The characterization of doped and mechanochemically treated materials will be analyzed by optical diffuse reflectance measurements and optical absorption calculations using the Kubelka-Munk approach. The phase structure and particle size of the materials will be determined using X-ray diffraction (XRD). The BET surface area of the samples will be obtained using an Autosorb instrument. The photocatalytic properties will be studied by the analysis of decomposition of Methyl Orange in an aqueous solution. An aqueous photocatalytic tubular reactor with capability of operation using UV and/or fluorescent light will be designed and built.

<p>This thesis describes syntheses and characterization of star-like amphiphilic block copolymers consisting of poly(ethylene glycol) (PEG) as the hydrophilic block,polycarbonate as the hydrophobic block and an amine-containing dendrimer as the core molecule. The macromolecules were synthesized by either a convergent or adivergent approach that includes tandem click reactions and ring opening polymerizations (ROP) of methyl trimethyl carbonates (MTC) with differentfunctionalities. The ROP of MTC monomers was performed using organocatalysts that allow mild reaction condition and reasonable molecular weight distribution(PDI~1.3). These synthetic approaches provide the resultant polymers with three different conformations, which are; mikto-arm type, comb-block with short PEGbrushes, and linear block with long PEG chain. The star-like polymers that were synthesized were all water soluble and most of them formed nano aggregates inwater. Different morphologies were observed in AFM study depending on the polymer conformation. Interestingly, some of them had indications pointing towards alower critical solution temperature.</p>

Arsenic is a toxic element that is widely distributed throughout the earth??s crust as a result of both natural geologic processes and anthropogenic activities. In virtually all environments, methylated forms of arsenic can be found. Because of the widespread distribution and toxicity of arsenic and methyl-arsenic, their adsorption behavior on soil minerals is of great interest. Although considerable attention has been given to the behavior of inorganic arsenic on mineral surfaces, little research has been conducted regarding interactions of the methyl-arsenic forms. The objective of this study was to compare the adsorption and desorption behavior of methylarsonate (MMAsV), methylarsonous acid (MMAsIII), dimethylarsinate (DMAsV), dimethylarsinous acid (DMAsIII), arsenate (iAsV), and arsenite (iAsIII) on iron oxide minerals (goethite and ferrihydrite) by means of adsorption isotherms and adsorption envelopes. Additionally, desorption envelopes were obtained using sulfate and phosphate as competitive ligands. Arsenic was measured by FI-HG-AAS. MMAsV and iAsV were adsorbed in higher amounts than DMAsV on goethite and ferrihydrite at all pH values studied. Although MMAsV and iAsV were adsorbed quantitatively at lower concentrations on goethite and ferrihydrite, as arsenic concentration was increased MMAsV was adsorbed in slightly lower quantities than iAsV. DMAsV was not quantitatively adsorbed at any concentration on goethite or ferrihydrite. MMAsV and iAsV exhibited high adsorption affinities on both goethite and ferrihydrite at pH values below 9 and showed decreasing adsorption above this point (more rapidly for MMAsV). DMAsV was adsorbed only at pH values below 8 on ferrihydrite and below 7 on goethite. MMAsV, iAsV, and DMAsV each exhibited adsorption characteristics suggesting specific adsorption on both goethite and ferrihydrite. Increased methyl substitution resulted in increased ease of arsenic release from the iron oxide surface. MMAsIII and DMAsIII exhibited no evidence for any type of specific adsorption under the conditions studied. Phosphate was a more effective desorbing ion than sulfate, but neither desorbed all arsenic species quantitatively.